A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
The patch you speak of is Microsoft's match, not mine. I wish I could control when they push it out, however you should have it by now. They assured me it went into global distribution. The patch does NOT remove preexisting phantom boxes. Those must be removed manually. The only truly effective way to remove the phantom boxes is by deleting the entire column or entire row. Scripts created by others don't seem to do an effective job as hoped and it is unclear why that is the case.
Historically, when the problem occurred, the phantom boxes would never occur in the worksheet in position 1 in the workbook. It was consistent on other workbooks. It would only occur in a worksheet when the cursor was left on a cell with a dropdown validation cell.
I hope your system is patched now and you have been able to fix your workbooks.