You have to flash it in Safe Mode. Non-Safe Mode wont flash it (I tried the same thing, and it did what you experienced). Dont know why that is, but Rick#2 will have to get it fixed, if he is even still working on it anymore.
I figured that out after, but each successful flash resulted in 5.5 getting stuck in the boot animation, so I just gave up and SBF'd it to get rid of all the convoluted mess it cased.