Hi Chris,
You should share more than one line of logs, logs in verbose mode tell a story 
Are you uploading a DICOM that is already in Orthanc ? If yes, Orthanc will have to delete either the new one or the old one and, in Hybrid mode, since the plugin does not know where the file is stored, it tries to delete it both from the local disk and from the blob. When it does not find it on the blob, it generates an error that is actually not an error (I already have a TODO about that).
For reference, this has been discussed here (about Google plugin)
Hope this helps,
Alain