Hi @pete ,
no I have not opened a ticket.
Nor have I found a workaround; we only used the upload to improve UX, so we did not role out that improvement. Users have to upload the attachments using the normal Confluence upload mechanism and can use them afterwards with our app / macro.
Maybe you have been hit by the general problem of AP.request, which is said to be fixed: Using AP.request to fetch content from the Confluence host has recently stopped working? and Log in with Atlassian account