Cannot open Numbers file in Excel

Suddenly in the last 6 days I can no longer open a Numbers file in Excel. The "Open with Excel" option is missing when right clicking on the Numbers file icon. If I search for Excel app I get an error that Excel thinks the Numbers file is corrupt. This happens on ALL Numbers files. Even if I create a new Numbers file from scratch with just the word test in the first cell and save as Numbers and try to open in Excel it says corrupt. I have rebooted multiple times. I have deleted the Excel cache folder and restarted. I have un-installed both MS Office for Mac and Mac Numbers and downloaded both apps fresh and re-installed. Nothing works. I can open .CSV in both apps no problem. I can open an Excel file in Numbers with no problem. The issue is only happening when trying to open a Numbers file in Excel. I have just spent 1 hour on a call with Microsoft Office support and they cannot identify the issue. I am running Monterey 12.6.2, Numbers 12.2.1 and Excel 16.68. All of these are the latest versions. All three say "software up to date" when I check for updates. As recently as last Friday I could open Numbers files in Excel by right clicking and choosing open in Excel. This issue has started sometime since Friday Dec 16th.