i was on 8.1 beta 2 and updated to 8.1 final then rebooted the machine. i noticed the title bar functions were no longer showing for some apps like the windows store or the settings app. though they do show up on the task manager app. also noticing that the skype preview app is lacking the title bar buttons.

im on win 10 64bit stable channel and got an update today, maybe they changed some underlying thing with those types of apps?

It looks like the issue is there for all Universal Apps