Can't call a function from a query WHERE clause.

Can't call a function from a query WHERE clause.

Calling a user defined function from a where clause doesn't fire the function.

Functions only fire once when used in a WHERE clause.

UDF doesn't fire when used in query predicate.

Function not firing in WHERE Clause.

When an ABL predicate (such as a WHERE clause) contains a user-defined function, the AVM evaluates the function once-when it opens the query or enters the FOR EACH block.   

For example; if the function returns a hard coded value like TRUE or 1, the WHERE clause will resolve to <field-name> = TRUE|1, otherwise the query will not be resolved and no records will be returned.

Resolve the value of the function prior to using it in the query predicate.

References to Written Documentation:
OpenEdge Development, ABL Reference, "FUNCTION Statement"