Hey, this is a known UI bug. The subagent card can get stuck on “Starting up” even though the subagent is actually running in the background. Your tasks should still run, the progress just isn’t showing.
As a temporary workaround, try Cmd+Shift+P then “Developer: Reload Window”. For some users, this brings the UI back until the end of the session.
The team is aware of the issue, and your report helps with prioritization. More details in this thread: Sub Agents wont run and are stuck at "New Subagent - Starting up"