Can you record the exact steps you take? This must be in combination with another action/keyboard shortcut, or with a third part app or it won’t open all windows. Where is the cursor located when you hit the keyboard shortcut? Or what has focus?
Agenda was the only open window, OmniFocus, Fantasy & Nitro PDF were sitting on the side in stage manager. It occurs only if there is no focus on the app. Open Agenda to an empty space and then escape leaving nothing focused. This is with the ⌥⌘␣ option in settings NOT selected. When selected all is well.
Also, it crashed the app for the first time doing this. I closed all agenda windows with ⌥⌘W as have been doing; it was windows closed and crash. Sent the report.