I have issue with response by Tau-Prolog

Question

I have a connect4 game implementation on the prolog. The get_next_board/2 predicate works fine in the prolog console.

But when I want to get the result using the session, it just waits for a long time for a response that never comes.

session.consult and session.query pass successfully unlike session.answer.

Console:

Code:

const session = window.pl.create();
// Consult
session.consult(program, {
    success: function() {
        console.log('success consult');
        // Query
        session.query(
            `get_next_board(
                [['1',_,_,_,_,_], 
                [_,_,_,_,_,_], 
                [_,_,_,_,_,_], 
                [_,_,_,_,_,_], 
                [_,_,_,_,_,_], 
                [_,_,_,_,_,_], 
                [_,_,_,_,_,_]], 
                X).`,
            {
                success: function(goal) {
                    console.log('success query');
                    console.log(goal);
                    // Answers
                    session.answer(x => {
                        console.log('success answer');
                        console.log(window.pl.format_answer(x));
                    });
                },
                error: function(err) {
                    console.log(err);
                }
            }
        );
    },
    error: function(err) { /* Error parsing program */
    }
});