Known Issue [as of 16/01/2014]:
If the user launches the Assembly Kit through the Tools section of Steam it will generate a file called steam_appid.txt in; C:\Program Files (x86)\Steam\SteamApps\common\Total War Rome II\assembly_kit\binaries
If the user then attempts to process a campaign start_pos through BOB it will NOT generate the start_pos.esf file because Rome2 will crash before it is able to start the process.
There is a work around – if the user manually deletes the file steam_appid.txt from the above directory it will work correctly, however if they launch via the Tools menu in Steam the file will be re-generated. This will not harm or affect the users game in any way.