MyBB

In the following scenario, I basically want to move all threads from
one subforum to another subforum. Some posts disappear in this
procedure.
Steps to reproduce the bug:

1. Make new install of MyBB 1.6.3
2. import the attached database
3. log in as bo198214 with password bo198214
4. Goto subforum "General Discussion and Questions"
5. Mark all threads of this subforum and "Move Threads" to
   "Mathematical Discussion"
6. Go back to the main page

You see "General Discussions and Questions" 1 Thread and 5 Posts.
But if you go into, nothing is there.

You see "Mathematical Discussion" 416 (3) Threads. Whatever that means.

If you look in the database table mybb_posts:
There are 8 posts which still have fid=2 (which is "General
Discussions and Questions") instead of the new fid=3 (which is
"Mathematical Discussion").
These are the posts with the pid's:
2548, 2549, 2556, 2559, 2560, 2561, 3365, 3366
All belong to tid=213

But as said these posts are not shown in fid=2, I guess because the
thread tid=213 has fid=3 already.

Later then when I removed "General Discussions and Questions" and made
a rebuild and recount, some of these posts got lost (not anymore contained in
the database).

I defer the attachment of the sql file, because my whole bugreport got lost, when I attached the 2.3 MB (while it was written that its possible up to 10MB), perhaps taking too long to respond.
This is worth another meta bug report, its really nasty when making the effort of a detailed bug report, which gets lost by some server response problem.