Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - General So where is that Linux version anyway?

The Enhanced Edition is the new branch of code referred to in the OP.
The release version was out of date when the last patch was released (with specific updates and fixes moved to that branch of code), while the Linux version was on an even older branch at the time. Updating the Linux engine for the release version and then again for the Enhanced Edition was not practical (and would have further delayed the Linux release), so it is just being updated for the Enhanced Edition.