I just did quite extensive Moodle XML export and import of questions in a course being used on a site that refuses to restore to any other site. What I discovered from that was, that the only questions refusing to be restored from Moodle xml were the new drag and drop matching containing audio, or at least mp3 audio. The ones that did not contain audio restored fine.
I wonder if anyone could try Moodle xml export of a dd_matching question containing an audio of about one minute's length. I'm pretty sure if this won't work, then a restore of a backup containing several of these will also refuse to restore - the exact problem we have been having.
Thanks in Advance,