On IBM AS400/iSeries/System i/IBM i - call it what you will - there are two types of index that can be created, a 'standard' binary radix index, and a distinct type called an 'encoded vector index'
This distinction is visible within Squirrel, when you use the DB2 plugin and view the index: the 'uniqueness' property says 'encoded vector index'.
So if you then use the create table script feature to generate the table and associated index, Squirrel has the info available to generate the SQL for an EVI correctly:
create encoded vector index ...
but at the moment you just generate
create index ...
which is wrong.
An enhancement to handle this case properly would be great.