there is a fix somewhere in the thread for this issue, unzip and copy a file to some folder, keep the old file, AFAIR I installed it, did all 3 (was it 3?) parts of that quest, but there was some issue with other event triggers with that fix installed, so - delete and copy back the original file, keep playing
one of the dev team reps here said no fix was necessary, but the fix helped my playthrough (everything else was finished, and this event just wouldn't trigger) and didn't seem to cause any other issues down the line, at least till the end of 0.57 that is