problems in using @mentions

 I'm the admin and today I encounter problems in using  @mentions in Box. When I type @, the list of users appears correctly, but selecting a user does not insert the mention. This occurs on multiple computers, multiple browsers (Chrome and Edge), and across all folders. Other collaborators in the same folders can use @mentions without issue, so the problem appears to be specific to my account and I am the admin of a business account. I appreciate any help!