Hey, thanks for the report. This is a known bug with the branch picker in the Agent Window on remote extension hosts in WSL and Remote-SSH. There’s a similar thread with details here: WSL branch list does not load, cannot use “Link to master”. There’s no ETA for a fix yet, but I added your case on 3.3.16 Early Access as another data point.
Things you can try:
Ctrl+Shift+P → Developer: Reload Window. Sometimes the remote extension host restarts and the branches show up.
In a WSL terminal, run time git branch -a. If the command itself is slow, it might not finish within the 10s timeout.
If the workarounds don’t help, send the number of branches with git branch -a | wc -l, and let me know if it also reproduces on a repo with a single branch. I’ll post here once there’s an update on the fix.