I have Bugzilla 2.20rc1 set up, though this happened with 2.18 also.
Most of the products work fine. However, one of the products gives us
a problem. There are 20 open bugs for that product. There is a group
set up Mandatory/Mandatory for it, but both me and the other admin are
in that group. If we do a search for open bugs in ALL products, those
20 bugs show up. We can access them, if we look at them they are in
the proper product, etc. However, if we restrict the search to just
open bugs in the problem product, none of the 20 bugs show up.