Command + Space no longer catchable
The system has defined a shortcut that intercepted this on my mac:


commandspace was bound in System Preferences to Select the previous input source in the Input Sources panel of the Shortcuts tab.


This setting might have been in effect already, but since I have only a single input source (US QWERTY keyboard), it may have been ignored before.

In any case, deselecting the shortcut fixed the problem.  Since it can be a pain to have to go fishing for a binding in all panels, here is an app (recommended by bmike) that shows you the current live shortcuts in any app as it runs.


https://www.cheatsheetapp.com/CheatSheet/