GSM unlocked i537 with code, but still locked sha256 is still 1 not 0 topic

I have bought a code an unlocked my i537 at&t S4 active.
The process went fine, the code was accepted and the phone said "unlock successful"
I even have a youtube video of the successful unlock.

BUT

it wont connect to any other network (im not in the US so I cant even see if it detects at&t)
When I try to connect to networks manually, it detects nothing. No GSM networks.
Ive checked and the sha256 enable flag is still (1). From what I understand, after a code unlock, it should be (0) is that right?

SO clearly I cannot connect to the 3 network here in the UK.
Does any one know what the problem might be? Anything obvious, or maybe a hidden menu setting in *#0011* and so on
Thanks.