Usd import into level, cannot delete

I was wondering if anyone could help me out here.

Whenever I import some meshes via usd, ‘import into level’ and I decide I don’t like one of the actors/meshes it has imported and delete it from my level, it keeps coming back.

Whenever I test the game by playing it or I save and load my level again, the actors I delete keep popping back.

Strangely, when I save the level, it recognizes that I’ve deleted them, yet they load back in when I reopen the level.

Does anyone know of this? and/or knows a way to delete the actor?

Many many thanks