Two incidents with invisible/silent mobs and NPC's:
Firstly, in Alikir, sneaking around above ground at Sala En, I was attacked by invisible mobs - dominion soldiers and swordsmen. Other mobs in this area were visible. I was not able to /bug this at the time on account of my character being dead. I respawned at the wayshrine, returned to the scene, and the mobs were now visible.
Second instance - travelled from Mournhold to Stormhold using the navigator. The loading screen into Stormhold took a couple of minutes to complete, much longer than normal. On arrival in Stormhold there were no NPC's visible or audible anywhere in the town. The NPC's were bumping into my character and pushing him around though. Tried to /bug this but the report would not complete in the time I had available. Later on, when I logged back in, the loading screen only took a few seconds and all the NPCs in Stormhold were visible and audible.
Nothing like this has ever happened to me before on the PTS or Live servers.
PC EU