Error messages: "The requested object could not be found", "Command failed", "Unknown error", "Object has been deleted", "the range cannot be deleted" --Issues with Track Changes
https://support.clarivate.com/Endnote/s/article/EndNote-Issues-with-Track-Changes?language=en_US
NOTE: Per call to Clarivate--Turn off all Track Changes while actively working on a document. Turn back on when done.
Jun 20, 2022•Knowledge Article
"The requested object could not be found", "Command failed", "Unknown error", "Object has been deleted", "the range cannot be deleted" and other messages may appear while formatting a document containing Track Changes. The document can also crash without a specific error message if Track Changes or Comments are visible in a document. With modern versions of EndNote™ (EndNote 9, X and later) you will need to not be viewing the Track Changes (Track Changes can be on, just not visible) to be able to format documents without the error messages noted above.
To work with Track Changes in a Word document turn off the viewing of this by doing the following: To turn off the viewing of tracked changes, go to the "Review" tab in word, and to the right of "Track Changes," you will see a drop-down menu. In the menu, you will change this to an option called "Simple Markup" or "No Markup" (depending on your version of Word, you will only have one of these available on this menu). Once this is set to "Simple Markup" or "No Markup" try formatting the document again and the error should not happen if it was due to this issue.