I think this might be helpful:
I tested saving a regular scenario saved game (like the Grand Campaign or War to End All Wars) and export that saved file and it worked . However when i tried to export a saved game that was from a EU2Vic conversion , it failed even when i started at 1836 . However , the country i'm playing on that saved file is also a huge empire so it may still point towards the possibility of the converter not handling the large numbers .
I did try to change the converted file's heading from "EU2Vic Converter" to "War to End All Wars (1914)" to test if that was the problem but it didn't work either .
There was so much hope in being able to string CK , EU2 , Vic , and then HOI2 DD that I really don't want to find out that my hard work in those games are now a waste and can't play them in HOI2 DD . Good luck in trying to solve it , I pray for a new patch for the converter !