So does anybody else have this issue of being in the menu or inventory or quest tabs, and get attacked, but even though you return to the game, your character gets stuck? I just died because of it and wanted to know if anyone else is having this problem. Maybe a lag issue or something, but it's very frustrating.

Yes, definitely encountered the same.   The pane will close but your UI is totally locked up for about 10 seconds.  You can see what is happening but do absolutely nothing during this time.  Very bad if you are being beaten on by some of the tougher mobs.

This glitch, and a couple of others, probably account for the vast majority of any deaths I've had outside of boss fights.  It's frustrating that most deaths - and the associated XP losses - are due to game issues rather than legitimate defeats. [Camera problems and getting stuck on inconsequential ground clutter being two other of my pet peeves - but I digress].

Dang, I hope they fix it soon. Something in my inventory got destroyed, which I wouldn't have minded if it was my own fault and genuinely died, but penalties for something you have no control over seems really unfair. I guess all I can do is try to avoid it until I'm in a safe zone.

Press the circle usually does it for me