I’m a total n00b with UE but I think this isn’t necessary anymore. Megascan Trees have both <Forest/Saplings/Field>_xy actors (under SimpleWind) and <Forest/Saplings/Field>_xy_PP ones (under PivotPainter). I was having this (forum link or reddit link) same problem until I replaced all the SM Foliage used by the Procedural Foliage Spawner with their _PP counterparts. Now the spawned trees behave normally again.