Joining a session in PIE with Auto Connect To Server disabled will crash PIE.
Note: this is not specific to the Multiplayer Shootout project used in the repro steps; this will occur in any project with a simple Create/Find/Join session approach to connection.
Reproduced in 4.9.2 binary, 4.10 binary, and Main (CL# 2761843). The Auto Connect To Server toggle was not available in earlier versions.
1. Open the Multiplayer Shootout project
2. Editor Preferences > Play > Multiplayer Options, disable Auto Connect To Server
3. PIE with 2 players
4. In one PIE window, click Play
5. In the other PIE window, click Find Games
6. Click the available session when it appears in the list
Head over to the existing AnswerHub thread and let us know what's up.