Images on a local SSD, no changes to anything. I literally just check my email and when I get back, adding a color label takes like 2 seconds to advance instead of immediately. Waiting an undetermined amount of time in the Preview window eventually allows the advance speed to go back to normal.
I tried that rescan option before I hit send here, and issue persists after relaunching PM6. If I sit here for 20 minutes without touching anything, the labeling advance speed will be immediate again.
Edit: Left Preview window open, went and took a shower. Came back and advance is immediate now lol.