Crash on dedicated server -> GetObjectFromNetGUID: Failed to find outer.

Hi Unreal Devs!

I’m getting this very strange error when a client is trying to join a dedicated server for an online multiplayer game I’m developing. I have a transition level (an empty level) and am using seamless travel to travel to a level. However, I sometimes get the following crash:

[ 2023.06.21-13.59.26:410][527]LogNetPackageMap: Error: GetObjectFromNetGUID: Failed to find outer. FullNetGUIDPath: [7]/Game/_Game/Maps/TransitionLevel.[5]TransitionLevel
[2023.06.21-13.59.26:410][527]LogNetPackageMap: Error: GetObjectFromNetGUID: Failed to find outer. FullNetGUIDPath: [7]/Game/_Game/Maps/TransitionLevel.[5]TransitionLevel.[3]PersistentLevel
[2023.06.21-13.59.26:411][527]LogNetPackageMap: Error: GetObjectFromNetGUID: Failed to find outer. FullNetGUIDPath: [7]/Game/_Game/Maps/TransitionLevel.[5]TransitionLevel.[3]PersistentLevel.[8]PhaseBP_C_2147478609

The game never starts, and I get a Error: Fatal error! in the server logs shortly after the error messages I showed above. Has anyone experienced this before?
Note that this happens intermittently, so sometimes the error occurs, and sometimes it doesn’t.