The ingame map voting "Esc/Voting/Maps/ is blank no maps showing but the maps are there if I tick where the maps should be and hit F1 the vote passes and the server restarts and map executes, but there is no map names showing it is blank.
This sounds like a problem with the fonts used for the map list. Can you check what happens if you change the font settings in ESC/silEnT/Fonts.
Changing the g_gametype value to 16 is indeed a weird one. Can't imagine a reason for it to have an effect like that and the g_gametype value is passed to all clients in the serverinfo. You can confirm the value with serverbrowser websites like TrackBase. Do note that all the values above 5 will display as mapvoting there. Gametype 7 is Team Death Match gametype, but that uses different cvar for enabling the map voting. These cvars do not collide no matter how they are set.