That button does not do miracles anyway, it facilitates your search, by going directly to the respective category, but if there are not in the POIs of the map, or between your personal POIs in the kml format, you can not find the mosque anyway.
I did a test and in Italy it appears that there are only 4 mosques, two in Milan and two in Rome, instead there are also in small countries, but their positions are not yet registered by those who deal with POIs......