Sems to be a crash with dynamic bitrate. Try disabling it in Settings -> Advanced -> Network -> Dynamically change bitrate.
Could you also post a session log from when it happened?
1. Press WinKey+R to open the Run dialog
2. Paste the following into the box and hit OK: %APPDATA%\obs-studio\logs
3. Find the desired log file (usually the latest) and drag/drop it to upload it.
Log filenames are generated when OBS is opened.