Currently our team can add bookmark files as attachments with a hosted service and directly to an enterprise database, however when we are trying to add a bookmark to an enterprise service, it is not supported. We are using Enterprise 11.3 and we thought that it was a bug, but after opening a support case with Esri, they were able to reproduce the issue on 11.4, and as the documentation does not mention the bookmark file as a supported file type in attachments, they couldn't log it as a bug and suggested we post on the Ideas page.
The purpose of this project is to map drainage assets and the workflow we currently use is to have our editors assigned to add and edit assets inside of a polygon and then our reviewers verify the work. We have a web map set up with editable services that is accessed through ArcGIS Pro. Our reviewers often need to communicate dozens of issues to our editors that are attached to a single polygon and the best way to accomplish this is through a bookmark file that can allow the editors to quickly zoom to a specific area that needs to be revisited. We also needed to move away from hosted services for this project so that we can better manage these important drainage assets and utilize attribute rules to calculate the amount of road mileage that has been mapped inside of each polygon.