Ok, i can only assume it's a confirmed bug now. I turned off any and all image compression in this file, used 255,0,0/0,255,0/0,0,255 in assuming any device would be able to display and recognise these colours, and replace colour still does not work on android.
I made a file to demonstrate it, mfa and apk here.
I've already made a thread about this but there was no response from devs so i thought here (and with examples) would be better. Thanks.