User authentication username control/incorrect

[slewislcm]

Hi,
I'm hoping someone knows this fix, as it's affecting us now, and can't seem to solve it!
User clicks 'login with 365', and it works fine, logs and creates account, but is creating the username with the '@domain.ac.uk' at the end, which we don't want.

So username should be '123456' on moodle, but it's being created as '123456@domain.ac.uk'.

And I can't work out how to restrict this. Also had this problem with the local_365 sync too. 

Any help would very appreciated.

thanks,

Simon