Has anyone else done this same technique to get the OTA on their Bionic? What I mean is, from a custom ROM, run ReleasedRoot, option 1, which should wipe the phone, create a fresh stock 886 /system, root and forever root. Then, apply the OTA. It sounds like it would work.
After running ReleasedRoot option 1 you're no longer on Liberty, you're back to the stock Bionic ROM, right? I haven't used that program at all so I'm asking you. Which brings me to a suggestion. Try other ways to achieve what you're doing, and see if you have better luck.
1. Use
Fastboot or the FXZ to get back to stock.
2.
Root the Bionic.
3.
Manually forever root by editing a file and adding 3 lines to the end as described here.
4. Apply the OTA update.
This is exactly what I did minus step 1 because I was already at stock. You could also try step 1 above, but then ReleasedRoot option 2, instead of my steps 2 & 3. My initial suspicion is that your phone is not quite back at stock, and the OTA is failing as a result.