I am having an issue that seems to only occur when I am trying to play via steam. In the PIE the join session seems to work fine. But as soon as I am trying to join a session via steam. the client finds the session but for some reason it goes back to the starting map.
classic PIE-vs-Steam difference. the session find succeeds, but the travel fails, so the client falls back to the default map. usual suspects in order:
- travel data. with a non-seamless join the client is told which map the server is on; if that map is not in Project Settings → Packaging → List of Maps (cooked builds only ship maps in that list), the join collapses and you land on the default map. PIE works because the editor has every map available. add every playable map to the list.
- double travel. if your code calls Open Level on the client after joining (some templates do it to “make sure” the right map loads), that disconnects the session and reloads the start map — exactly your symptom. after a successful join the client must not travel; the server pushes it into the right map. audit OnJoinSessionComplete for any Open Level / Client Travel call.
- subsystem fallback. check DefaultEngine.ini actually has the Steam OSS active (OnlineSubsystemSteam with bEnabled=true and the +NetDriverDefines). if the packaged build silently falls back to the Null subsystem (PIE reads editor config fine, packaged builds sometimes do not get the ini right), sessions “work” but the travel info is garbage. open the packaged client’s log and search for which online subsystem loaded — a “Null” line there is the giveaway.
- get the real error from logs. run the packaged client with a log window (add -log to the launch options) and watch what happens between finding the session and the map load: you will see either a failure line (missing map, session join fail) or a join followed by a disconnect. those two cases point at 1 vs 2.
most of the time with Steam OSS it is #2 — one extra Open Level call after join that worked in PIE because PIE was already on the right map.