I'm currently using the trial, and although I love the speed and quality of the software, I have the exact same problem and it really is a deal breaker. I do most of my work on a cintiq, but have a fully better-quality calibrated monitor ( the cintiq is calibrated too ) to check color and always keep a view on the "big picture".
I did some testing, and it seems very clear that Affinity photo only respects the color profile of the MAIN monitor at launch - that is, the monitor that contains the menu bar.
When my cintiq is the main monitor, the colors are all wrong on my calibrated monitor, and accurate on the cintiq. If I quit, change the menu bar to my calibrated monitor and relaunch, the calibrated monitor now has the correct profile applied, while the cintiq is completely wrong.
As much as I'd like to start migrating my photoshop workflow to affinity photo, this one bug makes it impossible.
Are the debs aware of this and working on it? Should I try to contact them through a different method?
I'm going to go ahead and purchase anyway, because I love to support good software, but it's currently not useful to me until this is fixed.
Thank you,
Andres