If you can't armor break after 212 press 1 before the full recovery of 212 and then bf3, it seemed a lot easier to execute when I felt I was special cancelling a "fake" s1. And when you understand the correct timing to catch a breaking opponent off a 212, try to perform it without the 1. I just have better execution when inputting a bf special move when I am using it as a special cancel, so maybe this can help you.
Now I also understand why they buffed the s3, there will be A LOT of players that will just miss the input and s3 a breaking opponent. Pre patch doing this would be a guaranteed punish for the breaking opponent. I'll take it because I was starting to use the s3 in my gameplan and now it's even better.
I still don't know if Skarlet's armor breaker is good, decent or bad. I changed my mind many times about it. It's probably just decent.