I may not be able to offer more help for your specifics.

I never use TIB_CONNECTION columnattributes and avoid design time
field names wherever possible.

What happens if you remove the entry?

In any case,personally, I would standardize on one or the other ASAP.

Also, I notice that the DOMAIN is not defined as NOT NULL and I wonder
if any missing values in the field are affecting your aggregation
calculations??

I hope someone else can be more helpful.

Clive.