Same problem here. I have tracked it down to the network or disk speed of the server vs. the client.
If the client has a fast disk drive (Solid State Drive) and the server has a old, actual spinning disk, disk drive, then when the server tells the clients to travel, the client gets throught the transition level load, and then the new map load very fast, and the server is still loading the transition map. Then the client’s final map is loaded but has no tick, and never gets a BeginPlay event either.
Looking in the C++ code for the core engine there is a property in NetDriver.h, float ServerTravelPause, that then is copied into the world as a countdown timer on the travel map loads (World.cpp NextSwitchCountdown). It can be set in Engine.ini with
ServerTravelPause=4.0
But has no effect in the Steam Net Driver. (It is used in tcpIp NEt Driver and WebSocketNetDriver)
The comment on the variables is " Amount of time to wait before traveling to next map, gives clients time to receive final RPCs @see ServerTravelPause"
Also in void UWorld::ServerTravel(const FString& FURL, bool bAbsolute, bool bShouldSkipGameNotify)
There is an intersting comment:
if we’re not already in a level change, start one now
If the bShouldSkipGameNotify is there, then don’t worry about seamless travel recursion
and accept that we really want to travel
“travel recursion” ?
So maybe the real question is: How does one get ServerTravelPause to work in Steam’s Net Driver?
P.S. This bug is a complete show stopper for Unreal Engine multiplayer. Better known as a “Critical Bug”