search in N-N relations broken if using a different connection?

Using SC 8.1.048.

Form with one N-N relation field set as double select and to use a different connection than the form (N-N Relations > [fieldname] > Identification > Connection).

Form works perfectly.

The issue is if I want to let the users Search the N-N relation field (N-N Relations > [fieldname] > Search > “Show search for the lookup records”).

At generation, SC returns a SQL error just showing the SQL Select statement that is set in the field (N-N Relations > [fieldname] >“SQL Select Statement”), but the form is generated anyway.
When run, the form is rendered with the search box above the double select field, but whatever I type in the search box, nothing is returned.

Can anyone confirm if it’s a bug or not?

As a workaround, to be able to use the search function, I unchecked the field’s Identification > Connection and converted the sql string in the field’s SQL Select Statement from:

 select field1, field2 from tablename

to

 select tbl.field1, tbl.field2 from dbname.tablename tbl

and now I have no errors at generation and the search of the relation field seems to work.