Tech-Hilfe im englischen ForumI did, and it fixed dawn/dusk effect.
I had this problem when I first installed the game, but it was not abrupt enough that I figured it was a bug. With the hotfix, and later the patch, I got a more gradual effect. I recently re-installed Divinity to test something under v1.29 then installed the patch, and was back to a very short dawn/dusk.
Adding "splotchproblem 0" to the end of the config.lcl (and hitting enter) fixed it.