Hello Kuuwahi,
This could be related to having Update 3. Update 3 was released during 4.12’s release cycle and, as such, we can’t guarantee that older versions of the engine will be able to support it. Unfortunately, as far as I know, there isn’t a way to revert from Update 3. I would suggest upgrading to at least 4.11.2 with this QFE or to 4.12.5 or 4.13 which both have native support for Update 3.