Can't upload screenshots "One or more screenshots aren't in the rgb space"

For last 2 days I can't upload any screenshot for a new version of the app. I am getting an error "One or more screenshots aren't in the rgb space" each time - I even deleted all the existing screenshots and tried to reupload - no luck. Tried png and jpg images with different export settings - nothing works. Is it a bug or there is something I should know?

How do you generate screenshots ?

If you do it with Cmd-S in simulator (select according to the type of device for which you need a screenshot), there should not be any problem.

they were done in photoshop, taken from the Unity Editor itself, all the other screenshots and games have the pictures made same way, never had any problems - but now I get this error even when uploading blank image of any format and any color scheme. Tried generating on both Mac and Windows - it doesn't change anything