Sublevels in a multiplayer cause problems with character movement on clients

We changed the project to use Level Streaming Volumes and after that we encountered multiplayer problems. The following problem appears in a build and in editor (when we have two clients (on the client side) or with dedicated server option on).

When we move a particle system (any particle system, even with default configuration) to a sublevel from master level we encounter a problem with replication of character data, it looks like some modules stop replication. Initially the server sets speed to 0 and MovementComponent lags( but at the same time we can look around with a mouse freely) and the main character moves with a much slower speed.

After death and respawn ( through manual SpawnActor and Possess, or through RestartPlayer from gamemode) server controller changes flag to local ( and in case of one connected player there appear two local controllers, one on the server and one on client) and the player’s movement physics turn off - MovementMode turns to 0.

We localised the problem and it is in sublevels plus particle systems, because any of the following actions fix this:

  • delete all particle systems from all sublevels;
  • move all PS from sublevel to master level;
  • delete all PSs from the project.

Here is a video: - YouTube

We found the answer. It was a mistacke on our side. In the sublevels properties static was On, that caused problems.