For comments in Proofing window, allow @mention notifications to users not shared to sheet. Currently, if someone is @mentioned on a Proof comment they have to be shared to the sheet to receive a notification. In many cases, confidential information is on the sheet and person commenting should only see the comment and not have access to the entire sheet. If someone has access to the Proof but not the sheet there is not way to notify them about comments in the Proofing window.
Here is a link to a Smartsheet community discussion on the topic including confirmation from developers that this functionality does not exist.
https://community.smartsheet.com/discussion/88162/proof-comments-mention-not-working-consistently
When I used WorkApps, I had the above functionality.
Further testing of WorkApps reveals significant issues with @mentions. When a report is used to filter out row, an @mention generates an email notification with two big issues.
@mentions in WorkApps for Proofs and Reports need major improvements.