Hello,
I have an issue too with the Online Subsystem EOS integration.
I currently use Online Subsystem Steam to create session/join session. I replaced the steam OSS with EOS and configured it correctly according the documentation.
When I get the IOnlineSubsystem the subsystem name is ‘EOS’ but when I try to create a session the game crashes when accessing the SessionInterface.
Assertion failed: IsValid() [File:C:\Program Files\Epic Games\UE_5.0\Engine\Source\Runtime\Core\Public\Templates\SharedPointer.h] [Line: 1063]
0x00007ffa410220b6 UnrealEditor-MultiplayerTPS.patch_0_PID_16516.exe!FUniqueNetIdWrapper::operator*() [C:\Program Files\Epic Games\UE_5.0\Engine\Source\Runtime\CoreOnline\Public\Online\CoreOnline.h:510]
0x00007ffa41022c75 UnrealEditor-MultiplayerTPS.patch_0_PID_16516.exe!UMultiplayerTPSGameInstance::CreateGameSession() [D:\Projects\Unreal Engine\MultiplayerTPS\Source\MultiplayerTPS\Private\MultiplayerTPSGameInstance.cpp:79]