Need to assign extensionattribute11 to samaccountname


We are migrating users from one AD to another. As part of this migration we are standardising the login ID to a Firstname.Lastname (Joe.Bloggs) format ..................previously we were using surname + first letter of firstname (bloggsj)

We have the desired new login id stored in extensionattribute11 on the old domain and I've configured the Quest workflow (see pic below) to assign EA11 to both UPN and samaccountname.

But the users still get their old BLOGGSJ login id on new domain post migration.

I'm sure I'm doing something stupid.