I experience the same with MySQL 4.1.16 and Mantis 1.05. When i sort by Updated, it doesn't seem to take Ascending/Descending.... Priority should be raised to High.

I have the same problem on 4.1.21 (slackware 10.2 + up to date stable patches)

Same problem - after my host provider has upgraded MySQL to 4.1.21 - sorting stopped working completely. All bugs are sorted by number, ascending, in the bug list view. Problem first appeared on Mantis 1.0.0rc4, remained after upgrade to 1.0.5. Version of PHP - 4.4.2.

Just found out that it has something to do with DISTINCT keyword in query:
"SELECT DISTINCT mantis_bug_table.* FROM mantis_bug_table WHERE mantis_bug_table.id in (...) ORDER BY last_updated DESC, date_submitted DESC"

When this keyword is removed, MySQL returns properly sorted results (if not - results are being sorted by Id).

Ok, done a crude hack - removed DISTINCT from line 856 of filter_api.php. Not sure what consequences will be, but i'm desperate. :)

DONT DO THIS AT HOME! (if you're not sure what are you doing)

We have the same problem (after MySQL was updated to 4.1.21-standard). After we've done what lioxa said, everything seems to be fine but - as he said as well - we don't know the consequences yet. Hopefully a solution will be found soon.

The bug has been reported to mysql developers

http://bugs.mysql.com/bug.php?id=21456