Hair has stopped taking colour in places?

The yellow is too dark for the pink I'm afraid. Have you done pale pastel colours before?

I have done them before, yes. This is actually a few weeks on, a bit faded.
I even added some proper strong undiluted but its just not holding, the yellow isn't too dark - I've coloured darker before.
If I coat a whole length it just gets to a couple inches from the scalp and it washes right off - as if its oily but... I've just washed it all over with baby shampoo.

I had a similar issue. Figured out I was diluting the dye too much with the wrong type of conditioner (cone free works best for me). But I see you didnt dilute it..and your hair is clean. So here is some other info I found when I was seeking a solution:

-If your hair is too damaged, there's a chance it wont hold color.
-If your hair is too healthy, there's a chance it wont hold color (lol wtf)
-Applying heat from a blow dryer did WONDERS to lock in manic panic on me... (I went to wash it out..and the water even ran clear  :o)

I know you said youve colored even darker roots before but I have to ask........did you color darker roots with *that* particular shade? Because like Janine said - I think the yellow might just be too dark. It has to be lighter than the dye you're applying and the pinkish purple here looks VERY light.

I'm sorry, but it is a bit too dark for that colour. If it "stuck" in the first place, all that's happening is that as it's fading the colour is appearing to disappear there first because it's darker. Essentially, too dark for that colour it is now. If it didn't take in the first place, then it's just that they're too dark for that colour in the first place. Pastels that pale need a pretty much white base to work properly. What I'm seeing here is the roots at pretty much the same depth, if not slightly darker, than the ends. That makes this colour too light to work on the roots.

What dye is this?

I got special effects Electric Blue
I got crazy colour Fire

I've been mixing them for years, the red lasts FOREVER, like months, (it'll fade to pink) and blue will last about four/five weeks.
Trying to get pastels I've used Aussie 3 minute miracle conditioner?

Yeah as I said before I tried just using the raw undiluted colour and its not stuck to the roots at all. The root is quite a light yellow - I've coloured darker, more orange roots before.

From reading around the only thing I found was maybe my hair was not damaged enough, its all new growth with one bleach but like... I've never had this happen before.
I've coloured darker roots, left dye on less time and had longer oil build up since a wash..

I best not be getting too old *shakes fist*

I got special effects Electric Blue
I got crazy colour Fire

I've been mixing them for years, the red lasts FOREVER, like months, (it'll fade to pink) and blue will last about four/five weeks.
Trying to get pastels I've used Aussie 3 minute miracle conditioner?

Yeah as I said before I tried just using the raw undiluted colour and its not stuck to the roots at all. The root is quite a light yellow - I've coloured darker, more orange roots before.

From reading around the only thing I found was maybe my hair was not damaged enough, its all new growth with one bleach but like... I've never had this happen before.
I've coloured darker roots, left dye on less time and had longer oil build up since a wash..

I best not be getting too old *shakes fist*

I would have suggested what Janineb said about your hair being too dark but if you say you've covered it before then my only thoughts are:
1. The US version of Aussie 3 Minute Miracle is loaded with silicones (I assume the UK version is similar) and buildup is keeping it from taking
2. The dye is old and isn't working properly
3. The dye is new and the reformulation isn't working as well

Maybe you could try a baking soda (bicarbonate of soda) rinse to rough up the cuticle for the spots that aren't taking?

I went through a period of using Aussie 3 Minute Miracle all the time, and I actually did come into this problem at one point too. It just took time, clarifying and a few weeks before it got back to normal.
On hindsight using Aussie 3 Minute Miracle was a bad move as it was a build up of silcones that lead to my hair not being properly moisturised and some real damaged happened last summer out of no-where.

Ah, yep, I take it back (well, partly, this pink is too pale for that yellow 🙂 ). Aussie could well be causing this if you're using it as a conditioner. The ends are probably damaged enough that they're still taking in enough dye and/or stained more.

Agreed, Aussie is cone-tastic.  You'll need to scrub it out with a clarifying shampoo and switch to silicone-free stuff.

Most cheap conditioners are silicone free (and most silicone free conditioners are cheap!) 
Pretty much anything in the ingredients that ends in -one is a silicone, but there's a few that are actually preservatives.  Sorry I don't have time to link to any lists right now but have a rummage through the forum, it's all here.
Off the top of my head, Tresemme Naturals and the Body Shop's Rainforest range are cone-free.

Oh I see, naughty Aussie! I just assumed its a nice white conditioner and sooo nourishing because its a "miracle" without really looking at it!!

The dyes are pretty old as well, had them both a few years now >_< looking to buy Goldwell Elumen colours soon? I heard they last aaaages!

I'm going over it all today with a fresh bleach and a different conditioner to mix. Going to try Schwarzkopf After Treatment that came with the bleach, can't see any silicones in the ingredients.

If it isn't taking due to silicone build up from the aussie products you just need to use a clarifying shampoo and re-apply the colour.
You only need to bleach if you want to lighten your base.
You can get results that last longer by selecting the right dyes. I think Elumen is a lot of money for what it is, you can get as good if not better results with cheaper products if you know the ones to pick.

I don't tend to use Aussie all that much, just this conditioner when I want to mix a lighter dye.

I tend to swap between Lush's Blousey, purple toner shampoo and tresemme - then baby shampoo before colouring. I don't really use conditioners, maybe an occasional oil if its feeling dry.

I wanted to re-bleach because its been a good 8 weeks or so and I wanted to get a nice light base for another shot at something vaguely pastel blue.

I thought about Elumen because when I saw my stylist he had some blues that had lasted at least a month so far. I tend to find each 200ml bottle between $10-25 on Amazon, bigger and about the same price as SFX.

If you use them it would be great to hear how they turn out for you, not many people here use them. I wonder if the blue uses the same silicone based delivery system that makes them practically permanent like Ions blues?

From what I've read so far they are very similar formula to Manic Panic but has some alcohol-type solvent that allows it to penetrate deeper into the hair, thus making it a bit more permanent. Apparently they fade from roots quite quickly though?

I'll definitely drop a review when I get some in the next few months.