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I use Sharks RTM Tool and I en-counted the same problem with selecting create a class.
However I used another method to just set stats and unlock all then go into private match and kill myself...
After that I go into a public game, get a kill then quit the whole game then go back in and it'll notify you that your classes have been reset, that's how you know it stuck.

Use Shark's tool for unlock all, it sticks, gives legit gun stats and no freeze (after the first time)