Thank you Jamie KR!

I simply followed your lead and turned on XPS Document writer:

I went to Control Panel > Programs and Features > Turn Windows Features on or off, scroll down the list, and make sure the Microsoft XPS Document Writer is checked.

And could subsequently send invoice pdf again (after upgrading from Win10 to Win11).

It took me a wasted hour following intuit instructions, scrounging around doing google searches, until I found your fix.  Shame on intuit.