Microsoft says new Outlook can't open some Excel attachments

Microsoft is working to resolve a known issue that prevents some users from opening Excel email attachments in the new Outlook client.
TechBooky

New Outlook Can’t Open Excel Files With Non-ASCII Names — Fix Rolling Out

Microsoft has started looking into a problem that is preventing users from opening some Excel file attachments with non-ASCII ...

Can’t open Excel attachments in Outlook? This annoying bug is to blame

The cause appears to be the use of non-ASCII characters in file names. Microsoft describes it like so: “Any user may be ...
XDA Developers on MSN

Sorry, the new Outlook app can't open some Excel attachments, says Microsoft

There is a workaround, though.
XDA Developers on MSN

I’m never going back to Microsoft Excel after mastering this open-source tool

Open-source tool that made Excel obsolete ...