I misunderstood when you said "That fixed both issues".

Ok, my suspicious were true, the problem is when Unity samples textures in Linear Space (that must be activated in Edit -> Project Settings -> Player -> Other Settings -> Color Space -> Linear). There is a bug in noesisGUI in that scenario.

This problem and the post-processor one will be fixed in the next version of noesisGUI, that we would like to release at the end of this week.

Thanks for the prompt responses and fixes.

Both problems fixed in v1.1.11!