This idea has been merged into another idea. To comment or vote on this idea, please visit RENXT-I-2865 Add capability to pull Lists on Attachment Tags.
After discussions with your team, we came to the conclusion that there is no way to create a query for Tags used in the Attachments section. For example, I created the tag "Profile" for any brief I created and uploaded to an RE account but I am unable to pull a list of all "Profiles" I've created at the moment.
We should be able to run queries on this. Redicouls that this is not an option yet.