Hey Christina,
there was actually a changelist submitted recently that includes some logic to unload assets via a new option in the asset validation settings.
This will unload assets individually and not through a GC, but it should work for that case.
The CL is 39298179 in //UE5/Main, or here on Github.
You’ll still need to update the commandlet to set Settings.bUnloadAssetsLoadedForValidation = true.
Let us know if this works out for you, I think it’d be worthwhile to fix the commandlet on our side to enable that by default.
Kind Regards,
Sebastian