Hi pring123,
Unfortunately the best advice I can give here is to add the blocking volumes around/within your BSP brushes. The reason this is what would be best in this case is that BSP brushes are hollow, so clipping can be a constant issue. Something that may help is to duplicate your BSP brush and then convert the type of actor to Blocking Volume. This will not increase the cost of the map based on your BSPs but should help with the collision issues you are seeing. To do this, select a BSP brush and use ctrl+c/ctrl+v so that it does not move the actor location. Then, go to the bottom of your actor Details Pane>Convert Actor>Blocking Volume (see attached image). While it will take some time, this would be the fastest and most efficient method to solve the error you are seeing without using static meshes.
