Transaction Disappearing

I have experienced this TWICE now, and it's incredibly annoying.

I have had 2 different accounts, my checking and credit card, have reconciled transactions disappear. For my checking account, when it happened I had to go back and re-reconcile 5 YEARS to figure out what had gone missing.

On my credit card, it's happened TWICE. First time, was same as my checking account. Had it fully reconciled, and transactions went missing. Had to re-reconcile 5 years to find them. Got it all caught up 8 days ago. Looked at it today, and it was missing transactions again! Fortunately I only had to go back 6 months and re-reconcile again.

I don't know if it makes a difference, but my database is stored on my OneDrive folder.

If anyone else has any ideas on why this is happening and how to fix it, I would appreciate it!