I also saw that issue, and I just fixed it with commenting out that ensure in the source, that ensure is just for telling you that something is wrong, but since everything works, its just not needed. If you don’t want to edit the UE4 source, you obviously can’t just comment it out.
And the reason why it’s only “failing” once is that ensures in general in UE4 are only breaking execution on the first time they are called. Later, they are ignored.