Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I tried the manual update again that Prius04 suggested and corrected the string to my current build info. The manual method worked and is another workaround. For those of us with Avast's suite, I will let Avast Premium Cleanup's App Manager find and install the latest Office 2021 updates. Until MS fixes the ridiculous mess they made with the 2406 update, at lease there are a few workarounds.