This is a known issue where Chrome is deprecating Sync XHR on Oct 22 2019, affecting WAC's ability to unlock file and shutdown gracefully. At this time, no timeline when a fix will be ready.
Per Chrome, https://www.chromestatus.com/feature/4664843055398912
Disallow sync XHR in page dismissal - Chrome Platform Status
Chrome now disallows synchronous XHR during page dismissal when the page is being navigated away from or closed by the user. This involves the following events (when fired on the path of page dismissal): before unload, unload, page hide, and visibility change.
www.chromestatus.com
First option, a temporary opt-out is available via Origin Trial "Allow Sync XHR In Page Dismissal": https://developers.chrome.com/origintrials/#/trials/active
There are two OOS Updates.
Update for Office Online Server: April 14, 2020
Update for Office Online Server: July 14, 2020
With this update, issue has been solved for Word.
Microsoft still are working on solution for Excel and Power Points. No ETA at this time. Do follow this post to get latest update.
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