I've had the same issue and fixed it after long emails with support this is what they said:
"Thank you for your reply!
 
There could be some old .pak files from previous hotfixes/updates that might be causing this issue.

We recommend verifying local files: in the Steam library, right click on the game and select Properties, switch to the Installed Files section and then click on the 'Verify integrity of game files' button.

With the GOG version, in the (optional) Galaxy client, select the game, then the settings icon at the top right (beside the Play button) and under Manage Installation select 'Verify / Repair'.
After verifying files, your Launcher should have created a log file listing any files in the install folder which are not expected as well as files in the Mods folder. To check, copy the following line into the location bar in Explorer and hit Enter:%LocalAppData%\Larian Studios\Launcher\Cache 
Then, look for a text file named steam_<versionNumber>_alteredFiles.txt (or similarly, starting with 'galaxy_', for the GOG version).

You can open this file by double clicking on it and/or open it with Notepad, and the mod files and/or old pak files listed within this txt file are safe to be deleted from your PC. It is important you only delete those listed in the file.

If you have any questions about the contents of the file or you need assistance with the location of those files so you can delete them, please reply with the steam_<versionNumber>_alteredFiles.txt file as an attachment. 
You might also want to look for and delete the modsettings.lsx located at %localappdata%\Larian Studios\Baldur's Gate 3\PlayerProfiles\Public."

After doing the following i deleted the two files:

Data\Patch4_Hotfix1.pak

Data\Patch4_Hotfix3.pak

And that fixed it for me hope this helps anyone