https://www.fjsoft.at/forum/viewtopic.php?t=31393
https://www.fjsoft.at/forum/viewtopic.php?t=31376
https://www.fjsoft.at/forum/viewtopic.php?t=31270
https://www.fjsoft.at/forum/viewtopic.php?t=31227
https://www.fjsoft.at/forum/viewtopic.php?t=31413
https://www.fjsoft.at/forum/viewtopic.php?t=31415
https://www.fjsoft.at/forum/viewtopic.php?t=31410
https://www.fjsoft.at/forum/viewtopic.php?t=31398
https://www.fjsoft.at/forum/viewtopic.php?t=31533
https://www.fjsoft.at/forum/viewtopic.php?t=31509
This issue has been there for a very long time, and it seems it's getting worse every day.

Use Reset sync history from time to time.

Regarding synchornization there are not many more options we can configure.
Problems might have sth to do either with Outlook or with communication between Outlook and MPE. Be it "redemption" or how Outlook mangles with data structures (Outlook 365 is giving me trouble with recurring appointments, even modifying them from VBA does not work as it should).