I think you may be victim to the missing posts problem that Doug has
reported.  For me currently 21793 is the top group in the Reviewed tab
under 21792 which is the fix to which it is replying.  On the theory
that for some reason you are missing 21792 I suspect what is happening
is a little confusion in the logic for BFAV2.  On the one hand the
message is marked as a review, so it is a 'reviewed' message.  On the
other hand it's group has only a single message.  This suggests more
than one path in the decision network for partitioning the messages
which may lead to other problems and should probably be put on the todo
list as something to examine.

Ken