Things repeatedly reset to their initial positions, Fog of war on occasion goes back to what it was about 2 sessions ago, layer positioning changes, The circles that appear during moments of lower frame-rate as if someone were holding down their left mouse button on the map.
PC tokens also on occasion get reset to a position they were in previously. The issue seems to get worse the more players are in session, usually making it almost unbearable when we have the entire party. Which I found out via logging into/Joining another campaign that I joined recently, and while I was having problems with my own campaign, I was able to get into the second one with ease.