Same issues here.
Only way i got it to work is by using SQL auth without enumeration (by specifing the instance name)
I was trying to get to the the bottom of it but frankly jus gave up.
How is the enumeration suppost to work? Is sudo/runas being used for this else i can't see how it should work.
It looks like custom domain login just isn't possible. You either specifiy credentials and use SQL login, or you use domain login and it will use the the credentials from the current user.
When i'm logged in as admin and try to run the script it works fine without credentials (using my current admin user credentials), but when i manually specifiy the same admin credentials it fails and the error on the sql server will be "Login failed for user 'DOMAIN\adminuser'. Reason: Could not find a login matching the name provided." because it is looking for an SQL login user with that name.
However to be able to use SC for enumration, the user must be member of the local admin group. But an SQL user can't be part of a local system group.
So the only reason i could see this work if it's runs sudo'ed as the credential user and then don't pass credentials on the sql connecting. However that was my starting position and couldn't get that too work, maybe because of the virtual lab seperated network and not being able to connect a DC?