Did you verify local files (for the Steam version)?
If you start a new game and customize the character, can you remove attribute points there and re-assign them?
Do you have access to another computer you can try the game on? Zip your latest save and email it to me (raze@larian.com), and I can try it here (LMK where you want stats distributed for each character).
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin\PlayerProfiles\<ProfileName>\Savegames' folder. In Windows Explorer, right click on the save folder and select 'Send To | Compressed Folder' to zip it.
The attributes should work the same as abilities... There is a difference in response to right clicks, though. The attribute + buttons and the background for that section can be right clicked to close the window, while neither do so in the ability section. I don't know if that might have anything to do with the problem, though.
Please email supportdos@larian.com, with a description of the problem and the report.zip file generated by the
D:OS support tool (for the PC version). The report will contain system and game information, any crash dumps, and your saved games (all but the latest can be deleted, if file size is an issue).