[Q] GPS will not lock on - tried different roms and stock, topic

Hi all, pretty much at the end of the line trying to fix this.
I bought the phone at the end of November, and immediately rooted it, S-OFF etc. The first ROM I tried was Android Revolution HD, and everything worked fine, except for the GPS. It enables, and using an app like GPS Test says I can see 27 satellites or whatever depending where I am. However, it just won't get a fix and lock on. Using Google Maps, it just says 'waiting for location', but never locks on.

So, I recently tried the ViperRom (android 4.4.4), but same issue.
So, I thought I'd put everything back to stock. I followed this guide: http://forum.xda-developers.com/showthread.php?t=2735235, and all the flags in the bootloader look as they should. Stock ROM also.
Still no luck.

So I tried converting it to a Google Play Edition running Lollipop 5.01, using this thread and the links graffixnyc provided.
Again, everything works, but the same GPS problem.

Does anyone have any suggestions..? I can't think of anything else to do :(

Thanks for any help!