Hey, this is a known bug in 2.6.20 and it’s already being tracked here: Run and Debug controls missing from Run and Debug panel in 2.6.20.
It happens when the activity bar is in vertical mode, the VS Code default. As @Sandy_Weatherby mentioned above, switching to the horizontal orientation brings the controls back.
Another workaround is Cmd+Shift+P > Debug: Select and Start Debugging. You can start configurations from there.
Let me know if the workaround doesn’t work.