Hey,
Seems there are a lot of posts appealing for information on this but not much actual information. 6.4 does not work hotseat with any difficulty setting other than medium.

Myself and a friend are trying to have the hardest possible campaigns and medium difficulty just isn't cutting the mustard, even with lots of sub mods on.

It looks like there was a time when the difficulty could be set without a problem? 6.1 or 6.2? Can anyone confirm?

Cheers!