I have known for decades that the Date Last Edited field in RM and its predecessor are unreliable. The date can be changed when the person is not changed, and the date can fail to be changed when the person actually is changed. I’ve never tried to make a comprehensive list of all the situations like this that can occur. But I have just been bitten by one of them.
Namely, for the last couple of weeks I have been doing all my data entry into RM8 and still keeping my RM7 database as my master database. After entering data into RM8, I am exporting the new data to GEDCOM, importing the GEDCOM to my master RM7 database, and merging the duplicate people that result.
I just processed an obituary in RM8. The Date Last Edited field was updated in RM8 for the person who had the obituary. The Date Last Edited field in RM8 was not updated for siblings where all I did was pasted the obituary to the siblings as a citation. I double checked, and the behavior of the paste of a citation was the same in RM7. Namely, the Date Last Edited field was not updated just because of a new citation.
In my obituary scenario, I’m able to to use the citation for the obituary itself to find all the individuals who need to be exported from RM8 to RM7, and I’m sure I haven’t lost any data. But it’s certainly worrisome. Also, I don’t do the manual sync between RM and Ancestry using TreeShare. Rather, I periodically delete my Ancestry tree and reload my RM database in full to Ancestry. But I think I remember users reporting that simply adding citations to RM does not trigger the person with the new citation being added to the change list for TreeShare. I may be remembering incorrectly, but if I’m remembering correctly then I think it’s bug that needs to be fixed in TreeShare.