I have a SharePoint online environment and a requirement to copy thumbnails of the photos uploaded to an asset library to another library. SharePoint stores photo thumbnails in a folder called "_t" in the photos library.
I have tried to use a SharePoint Designer workflow (with the trigger on item creation) to utilize "Call HTTP Service" action to call SharePoint RESTful service http://server/web/getfilebyserverrelativeurl('URL to the thumbnail in _t')/copyto('destination library file URL'). When I try that it errors: "You cannot copy or move files either into or out of a picture library image preview folder." I don't think it makes sense to restrict copying FROM a preview library, but anyway I was wondering if there is another way of copying files. Any other solution to my business requirement is also appreciated.