Same problem here too, just word not excel.
Spent maybe 3 hours with Microsoft tech guy, tried everything, including a clean re-install of office - note this is not the same as uninstalling and re-installing office, you need to use a special app you download. He couldn't even load a previous version of Word. That was a pain using CMD, copying stuff off a notebook from a website etc. And didn't work.
He went away to ask about it and came back saying they've got loads of tickets on it. So I'm just waiting for the next version/build. Something else worth noting is that after we re-installed Office365, Word was version 2108. But after clicking update in Account>update options, it upgraded to version 2109. So the version on my 365 account isn't latest one, strange.