DoesPackageExist Warning flooding output log in PIE

I’m using a compiled version of the editor from the 5.0 branch on github, I’ve got a world with world partition enabled and I added a 4km landscape. Everytime I play in editor I get a flood of this:

LogPackageName: Warning: DoesPackageExist called on PackageName that will always return false. Reason: Input ‘/Memory/UEDPIE_0_WorldMap_MainGrid_L5_X0_Y0_DL0’ is in a memory-only mount point.

Is this a bug or do I have something set up wrong?

Exactly the same bug, been trying to fix last 3 days.