You should be able to save/load in combat, as well (named or quick).
If you get stuck using a skill like that again, and can not quicksave or hit Esc to bring up the menu to save, try clicking on the menu button on the far left side of the skillbar; that may still work.
This is a known issue, the main cause of which was fixed in the last major update. A handful of people have still reported this in the most recent update, though. If you still have any saves where this had occurred, please email supportdos2@larian.com, with it/them (or a Dropbox or Google drive link, etc) and a brief description about what was happening when this started (ie entering combat). Since you were quicksaving, they've probably been overwritten, but please keep this in mind if it happens again. Even better would be a save before it occurs, with a way (at least semi-reliably) to reproduce it, but so far nobody had reported a way to trigger this problem.
The programmer looking into this was not able to reproduce it in the latest game version, so at least having save(s) with 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'.
