EXC_BAD_ACCESS on Dynamic NavMesh

I am working on functionality for procedurally-generated and player-generated buildings within a game. To do so, I enabled Dynamic Mesh Runtime Generation. I would’ve used Dynamic (Modifier Only), but this has the limitation of not allowing me to add onto the existing navmesh, so it won’t work for multistory buildings.

The issue comes after the game has been running for a few minutes, where I get an EXC_BAD_ACCESS exception in the FRecastTileGenerator::GetTileX() function. It’s being called from FRecastNavMeshGenerator::AddGeneratedTilesAndGetUpdatedTiles
Considering this function just returns an int32 property, it’s unlikely the function itself is the problem, it’s more likely that the Tile Generator instance is a nullptr, but I can’t figure out why this crash is happening.

I don’t have any custom Navigation code, and for that matter the crash happens long after the procedural buildings are spawned in (and player-generated buildings are not implemented yet). The only thing affecting navigation as far as I can tell is NPCs walking around, but that alone isn’t the cause for the crash.

Has anyone dealt with a similar issue or can help understand what is causing the error?