Incorrect Date Formats in Microsoft Excel Files

iMac (21,5-inch 2017)Operating System: macOS Ventura Version 13.7.5

Microsoft Office Software: Home & Business 2021 for Mac

Recently both Apple and Microsoft released upgrades for: 

a) macOS Ventura to Version 13.7.5

b) Microsoft Excel to Version 16.95.3

I installed both upgrades, doing the Microsoft Office Home & Business 2021 for Mac first. 

Prior to installing the Microsoft Office update the date formats in Excel were set as dd-mmm-yy and when entering the date as 1/4 the result in the Excel workbook displayed as 01-Apr-25. This was also the case after installing the Microsoft updates. I then installed the macOS update and rebooted my Mac. On entering the date as 1/4 into an Excel workbook the date now displays as 04-Jan-25, irrespective of trying to format the date as dd-mmm-yy. 

I contacted Microsoft Support and spent more than 75 minutes on an online chat that included Microsoft Support assuming remote control of my Mac. The Microsoft support person exhausted all troubleshooting steps to format the date to display as 01-Apr-2025, but wasn’t able to resolve this issue. The issue has now been escalated to their higher technical levels and I await their feedback.

Perhaps the upgrade to Ventura 13.7.5 may be causing this date formatting issue?

Any guidance will be appreciate as it is very frustrating having to now capture Month/Date into an Excel workbook when I have captured Date/Month for years.