Unable to drop in actors or swap scenes

I’m setting up a new campaign with a friend and as we started building out the world, scenes, etc. we realized we can’t drop in actors or swap scenes. When we do the scene just shows up as blank despite knowing it’s loaded.

Any ideas on what’s happening here?

This could be a RAM issue of sorts.
Could you show me in some way what is happening when you try to drag out actors onto the table?
Maybe there is a console error (f12 → console)

As an update, after going into f12 console I found that perfect vision and roof tiles modules were killing the load of drops