This is not a bug
Sorry I should have warned you, here are the changes in ver 6 :
Requires Civ 5 ver 1 03.142
New Tech tree : you start with Fire and need to research Tribal Leadership to get access to the first buildings.
New Unit : Volley Gun : Original Civ 4 unit by Rabbit, White, conversion by Wolfdog.
New Unit : Culverin : Original Civ4 unit by The_Coyote, conversion by Wolfdog.
City Defense Unit line is now :
Archer --> Composite Bowman --> Longbowman/Crossbowman --> Culverin --> Volley Gun --> Gatling Gun --> Machine Gun --> National Guard --> Mechanized Infantry
Super Heavy Tanks now require the Project "Mammoth Tank" to be completed.
ANZAC Desert soldiers from Wolfdog as Infantry for Polynesia
ANZAC Jungle soldiers from Wolfdog as Infantry for Indonesia
Zero requires Kerosene
Pikeman (and Landsknecht) : upgrade path back to vanilla = the Pikeman upgrades as a Lancer.
Heavy Tank : upgrade to Modern Armor instead of Super Heavy Tank (because those are limited to 3 per Civ).
Iron : revealed with mining
Watermill : maintenace cost reduced to 1
Stable : help text updated : the Stable provides 3 additional Horses.
Holy War : must be build in the Capital which must be a Holy City.