Could you please elaborate a bit on the problem? What actions do you perform, what do you expect to happen and what is the actual result?
i seem to be able to reproduce this in the 3.0 branch svn head.
go to monitoring -> maps, open a map that has some problem with severity < disaster.
set the severity filter to 'disaster' - the problem is still listed
On map, when select filter with, for example disaster severity, prior to documentation i will only see problems with disaster severity. But, I can see all problems independently on severity. So, filter don't work!
Thank you! 
We might wish to also fix ZBX-10729 and ZBXNEXT-3321, if possible.
(1) ZBX-10729 has been closed as a duplicate - must be tested
vitalijs.cemeris I reopened ZBX-10729.
gunarspujats CLOSED
(2) No translation string changes.
gunarspujats CLOSED
Fixed in development branch svn://svn.zabbix.com/branches/dev/ZBX-10918
(3) Removed redundant validation in r60854
vitalijs.cemeris CLOSED
Successfully tested, but close (3) before merging!
Fixed in:
- pre-3.0.4rc1 r60857
- pre-3.1.0 r60858