Error: Actor ... has an invalid HLOD level

I haven’t used foilage painter before, but its the only difference I could think of
Just did a search for foilage painting and HLODs…seems there is a bit of trouble going on there

Re - Runtime Hash Class, I don’t really know.

There should be a way

In HLODSetups, try giving it a name and ticking the Spatially Loaded setting