Pengines success event produced with two different term structures

General
1

I’m using SWI-Prolog v 9.3.29

Why am I receiving success events with two different structures from the same Pengine ?

After starting my local Pengines server,
If I use this code:

% Test client for the pengines server
test_local_pengine :-
    % Create a pengine connected to local server
    pengine_create([
        server('http://localhost:3030'),
        application(genealogist),
        ask(ancestor_descendant(mike, _X))
    ]),
    pengine_event_loop(handle_result, []).

handle_result(success(ID, Bindings, More)) :-
    ...

I get success events that look like this: success(ID, Bindings, More)

On the other hand, if I use this code:

% Test specific queries
test_genealogist_queries :-
    pengine_create([
        server('http://localhost:3030'),  % not required if on the same host
        application(genealogist),
        id(ID),
        destroy(false)  % keep pengine alive for multiple queries
    ]),
    
    % Test multiple queries
    test_query(ID, q1, 'Find all ancestors of sally', ancestor_descendant(X, sally)),
    pengine_destroy(ID),
    writeln('<--- Destroy pengine after all queries').

test_query(ID, QueryName, Description, Query) :-
    format('~n--- ~w: ~w ---~n', [QueryName, Description]),
    pengine_ask(ID, Query, []),
    format('<--- Ask: ~w: ~w~n', [QueryName, Query]),
    collect_all_solutions(ID, QueryName).

% in seconds
timeout(0.1).

collect_all_solutions(ID, QueryName) :-
    timeout(Timeout),
    pengine_event(Event, [listen(ID), timeout(Timeout)]),
    ...

I get events with this structure: `success(_, Bindings, _Projection, _Time, More)`

Thanks.