OK - so it is this still an issue? Because we are not able to reproduce it.
Possible reason why it wasn't working and now it is, is because RSS channel shows other messages right now. So it is possible that some issue exist, but it is rare and we do not know now what it is.
For sure - it is not because of vBET cache - RSS has it's own vBulletin's cache so for RSS translations vBET cache is not used at all (it appears to be better for performance).
I will leave this thread open for some time. As I wrote we are not able to reproduce it on our side. So if I can ask you please monitor your RSS channel and check it from time to time. If you find this issue again it would be best to copy and give us links to every post which was shown in your RSS channel. This way we will be able to put it to our test forum, see exact content and work on it. Please stay in touch with this issue.