I've experienced the same problem - the dates on my recs appear to have jumped forward into 2019 and it's also pulling transactions from 2017 in to the reconciliation. I've used the Undo function to get back to where the issue seems to stem (October 2018) but the opening balance is now completely wrong. I ran the Verify and Rebuild functions - no issues. The discrepancy report is zero. I have no duplicates. I really don't want to have to go back to the beginning of time and re-run the recs, particularly if as I've read here, the problem re-occurs. I use QB Desktop Pro 2017. Can anyone advise what to do?