Weird inconsistencies with the maps and starting new games:
If I just click on "Set up a new game" from the Games tab I go to the
create game page and the map section has tabs "Default" &  "Yours".

If I go to the Maps/Your own page and then click on a map, and then
click on "Start a game" I get sent to the create game page and the map
section has tabs "Default", "Yours", & "Custom" with my map loaded up
in the custom section - presumably ready to start a game.

Here's where things get odd. If I try to start a game using this
"custom" version of my map I get slots for 4 players regardless of
the number of players the map supports (more or less). However, if I
click the tab to "yours" and choose that same map then the player
slot count is correct.

I'm guessing this is a bug, but also what is the purpose of the
custom tab in general?

Hey - this is clearly a bug. Thanks for pointing it out.

The custom tab is a place to hold any map that is selected elsewhere. E.g. when you want to play on somebody-else's map which you can not normally reach from withing game start.

If you use the same mechanism for one of your own maps the map becomes available through custom and yours simply becasue we are not checking if the map is one of yours.

Hope this makes sense.

Yep, sure does thanks.  Just for clarification, you also only get a choice of only 4 players if you choose a map other than your own via this method.