Another snag I’ve run into while using Mu4e was that sometimes I also use Apple’s Mail on macOS and iOS and any messages I delete there would only be flagged as “trashed” in Mu4e, so they would show up in the inbox, cluttering things considerably. The fix for this was to set Expunge Both in my .mbsyncrc file. Also much better! That one has been bugging me for a long time.

Source: A couple of Mu4e improvements | Baty.net

As with all its services, Apple offers no real troubleshooting when iCloud Drive synchronization stalls in macOS. Glenn Fleishman encountered a problem that took months to diagnose and fix. In the process, he went through the wringer of trying nearly everything suggested online, via Apple support, and from colleagues. In the end, the magic that fixed it was undisclosed engineers.

Source: Cloudy with a Chance of Insanity: Unsticking iCloud Drive – TidBITS