I've completed every single challenge twice for every character just to make sure (yes I got the pop up that says it was complete) but the only characters it gave me was bat agent and hunter...Not to mention they fixed it so we can get supply drops again and decided to give me five for free despite the fact that I'm missing about 70... Good job, you added snow and a tree now give me my *****?
Are you sure you're doing the challenges in multiplayer / custom matches? I inadvertantly did the survivalist challenges in local mode and while it awards the accomplishments, it doesn't unlock the charachter. Doing the challenges in multiplayer again awarded accomplishments and did unlock charachter.
Do them in custom match so your "allies" won't mess it up.
For survivalist, most people seem to get confused on the mysterybox challenge. Instead of just buying the box twice or none at all, you have to buy the box twice and use ONLY those to guns until wave 30 is completed. So use only the shovel until you can buy the box, and restart if you get the monkeys or anything other than a wall gun like the thompson (the best gun in the game imo).
Assassin- Don't even press the button for the tubes to open in the PAP room, and use frontline when placing batteries on the panzer to avoid skipping rounds on the wave 12 challenge
BAT Elite- Good luck on getting the wave 16 and 75 minute challenges right now because atleast 1 of the tesla batteries seem bugged right now.
Ok so evidently they fixed it and instead of giving me the characters I should have already unlocked they just reset the challenges that glitched so all I need to do is complete them again. Thank you guys for trying to help though. They really need to stay on top of this stuff and start monitoring the forums so they can reply and help themselves instead of expecting us to help eachother.