Error 132 on Onyxia's realm

I'm getting Error 132 consistently while trying to access the new progressive realm Onyxia.
It pops up right about when the Vanilla assets start loading.

Things that I've already tried to no success:
- I have tried redoing the Large Address Aware Patch to allow the game to use more memory.
- I have made sure no files within the game folder are Read-Only.
- I have renamed Interface, Cache and WTF files to allow the game to create new fresh temporary files.

Things I suspect might have something to do with the issue:
- I have currently installed a couple of texture patches from later expansions.

Things that I've not been able to explain yet:
- Yesterday I could get inside the Vanilla realm no problem, with all my addons, texture patches and everything else.
- I currently can still get inside the Icecrown realm with no problem with all my addons, patches and everything else.

I'm having a hard time making sense of what is triggering the error or coming up with new possible fixes to try. Any ideas?