Upgrading from 4.1.0 to 4.2.1 Mautic Died

I finally got the instance up and running, however I am still not able to update the schema correctly and as such certain things are not working, for example I cannot load segments.

The main problem from what I can see is

SQLSTATE[42S22]: Column not found: 1054 Unknown column '@' in 'generated column function' 

Where the query that is running is

ALTER TABLE leads ADD generated_email_domain TEXT(255) AS (SUBSTRING(email, LOCATE("@", email) + 1)

It seems that from what I can understand it is looking at the leads table and the column emails, and trying to split this column based on a delimiter of @ which is proving problematic.

Once again hoping to get some help from someone that understands database stuff.

Thanks