This is straight from the Pixel Experience website:
"You are attempting to migrate from an unofficial build to official PixelExperience. A full data wipe is needed if you are coming from something other than an official build of PixelExperience."
Frequently Asked Questions - PixelExperience Wiki
wiki.pixelexperience.org
Only problem is that you said you did wipe the device which should have fixed the issue. The only thing I can think of now is to start from scratch.
1. Restore with MSM
2. Upgrade to OOS 11
3. Unlock Bootloader
4. Install Pixel Experience Recovery
5.Wipe
6. Install Pixel Experience