Hi Minkiton. I’m RN, an Independent Advisor and Microsoft user like you.
I'm sorry to hear about this issue.
May you try to run your Excel in safe mode?
- Find the shortcut icon for your Office application.
- Press and hold the CTRL key and double-click the application shortcut.
- Click Yes when a window appears asking if you want to start the application in Safe Mode.
If there is no issue in the safe mode, possible that there are add-ins that blocks you from using the Developer options while in normal startup. Check add-ins and disable them while in safe mode, then restart Excel and open it in normal mode to see if you can access the XML functions.
If problem persist, completely uninstall Office with the uninstall support tool (option 2) and install it again. See article below.