That is the expected behavior. Unfortunately, the bug reporting
system is a bit of a black hole from outside of Apple.
Wait a second - the original poster said his bug reports were
actually disappearing completely from his view; that's not expected
behaviour. Every bug I've ever filed is still there, marked as
'Duplicate', 'Cannot reproduce', 'Closed', etc.
At least, it wasn't up to about a week ago; has something changed?