Why is Quicken randomly changing categories on transactions (even reconciled) after updating account

Question

I am a LONG time Quicken user/subscriber and am experiencing a very frustrating issue that is starting to make a paper register look better.  I diligently enter transactions to the account registers at several banks with the appropriate budget category being careful to input transfers as transfers with the offsetting account input to the category field.  I download transactions and reconcile daily usually without an issue until that RANDOM day (appears to be at end of month, every month lately) Quicken removes all categories from the transactions, even reconciled transactions during the update process  Every month I have to manually re-input all categories.  VERY frustrated ... Quicken support please chime in on this ASAP with a resolution.

DianeB · Answer

Thank you @"Tom Young" .  The restoring of backup doesn't solve the issue as it happens again with the update afterwards.  I did turn off syncing as that sounds like a reasonable cause.  Crossing my fingers it works.

Tom Young · Answer

"Every month I have to manually re-input all categories."Are you having Quicken make a backup automatically every time you close Quicken and making sure that several days' worth of these backups are maintained?  If so, instead of manually entering Categories for every transaction I'd simply restore "yesterday's" backup and try again, but maybe you've done that and the removing of all Categories happens again?Are you "syncing" your file so that you can use mobile?  If so, I'd suggest turning that feature off and seeing if that corrects the situation. 
Other posters have mentioned the same problem related to CitiBank: 
https://community.quicken.com/discussion/7887431/has-anyone-experienced-categories-being-deleted-when-updating-citibank#latest