Error when attempting to import meshes

Hello! I’m currently trying to import a map I had modelled. It says that the import is successful, but the map doesn’t appear and I get this error:
“exception while signaling: invalid unordered_map<K, T> key”.
Does anyone know a fix to this error? It’s been happening for a long time already. I’m using the new “Import 3D” button from the home tab, and the files I’m importing are FBX.