Is this just my problem or has it popped up for everyone?
I set a net color and that works fine. Do a few more (typically power nets), seems to be fine. Hit F5, nothing. Try via the view menu - enabling and disabling net color override has no effect. Open a different schematic page and that shows, or doesn't show, the net colors according to the setting, but once it's open no amount of toggling the setting changes things. To see any change, I have to close the document and then open it again.
I am pretty sure it used to work dynamically as intended, but closing and restarting Altium doesn't fix it.