new bug in script using count() function

When attempting to import a Deluge script to create an application, this line:

lC = count(Location[unique_id == e.unique_id]);

Is resulting in:

Error in statement at line number 1614
Though the column is unique, the operator does not check for equality, so the statement might return more than one row.

This statement used to work fine and the error message looks new to me.

Can someone explain what the trouble is?

Thanks in advance.

-pete