1) This is a known issue.
2) This is also a known issue, but should have been fixed in Wednesday's update. If it happens again, saving and reloading should restore the character (that can be done during combat).
If it happens again, please email the save(s) (or a Dropbox or Google drive link, etc) to supportdos2@larian.com, with a brief description of which character was stuck and what was happening when it started (entering combat, etc).
Even better would be a save before it occurs, with a way (at least semi-reliably) to reproduce it, but so far nobody has reported a way to deliberately trigger this problem.
Loading the saves fixes the problem, but at least having information about the state of everything when the bug occurred could help in tracking down the cause.
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin 2\PlayerProfiles\<ProfileName>\Savegames' folder. In Windows Explorer you can zip a file or folder by right clicking on it/them and selecting 'Send To | Compressed (zipped) Folder'.