Is this some known issue I am not finding? When I do export to .CSV, it works and I can open it in Excel. However, when I excel default file option (.xlsx), then it shows this error:
"Sorry, we couldn't export your visual data right now. Please try again later."
I also verified that export data to .xlsx still works for me(North Central US Data Center).
As we cannot reproduce the issue, I would suggest you create a ticket on Power BI Support for better assistance on this issue.