Sorry for the Necro.
I was having the same problem in UE5 with regards to collision not functioning correctly. My third person character was floating above some of the terrain and passing through other parts of the terrain. The way I fixed it…
Click on your Landscape actor, search for LOD Distribution and my LOD 0 Screen size was a bigger number than my LOD 0. I set my screen size to a lesser number than my LOD 0 and the problem was solved.