This was reported by a couple of users in June and, after much head scratching, I tracked it down to the fact that they were using the attachment_preview plugin. When the plugin is disabled, the issue is not present.
I opened a GitHub issue and the plugin developer and I were in communication for a little while, but it didn’t lead to a resolution.
Until whatever in that plugin is mangling osTicket Awesome’s jQuery code is fixed, the only solution is to disable the plugin by going to Admin Panel > Manage > Plugins.