Numbers app

Yes, that's the exact problem I've seen. What worked for me was this: instead of simply tapping the attachment, long press (press and hold) until a preview and options appear. Underneath the preview, tap Share. Don't tap the preview itself.

This may be a crash similar to one I've seen when trying to print email attachments. Please try this workaround: when looking at the email, long press (press and hold) the spreadsheet attachment icon to bring up some choices. Do you then have an option to send it to Numbers, possibly via Share—and does it work?