Noticed this in one of our examples, while trying to disable a button from a slot attached to the 'clicked' signal (that's the app's logic): the button is, indeed, disabled (cannot press it anymore), but this change is not visualized (button still looks like it's enabled). Cmd-tab between different apps (and back to my app) fixes the button's appearance to 'disabled'.
I set 'Component' == 'macOS (cocoa)' because it's reproducible on macOS only, on Ubuntu my application does not have this problem.