We've been using office web apps in our SharePoint 2016 farm for over a year. A few weeks ago it stopped working. There weren't any updates installed and we're told there weren't any GPO updates.
I found one post on this site around WMI, but that didn't fix our error.
WordDocumentSessionServiceWatchdog reported status for WordDocumentSessionService in category 'Ping'. Reported status: WordDocumentSessionService ping hit an exception.