In earlier versions of Zabbix, if a map was configured to filter out problems by applications and then used as submap in another map. The other map would also respect that filter.
I guess after applications were removed and we introduced tags instead this no longer works.
While the submap itself only displays problems according to the filter, if used in another map - tag filters are ignored.

The previous version we are sure about, where this worked as expected is 2.4