hitTest returns null when ctrl/shift/alt is held targeting an already preselected subassembly

Question

While calling hitTest on an already preselected group of nodes, meaning, nodes in parent/child relationship preselected previously using select, and at the same time, holding down either shift, alt or ctrl the hitTest call returns null.

Is there another way to get dbId of a node from a preselected subgroup of nodes under cursor when a modifier (shift, alt, ctrl) key is held down?

    private getDbIdAtCoords(x: number, y: number) {
        const viewport = this.viewerWrapper.viewer.container.getBoundingClientRect();
        const result = this.viewerWrapper.viewer.impl.hitTest(
            x - viewport.left,
            y - viewport.top,
            false,
        );
        return result ? result.dbId : 0;
    }
    ...
    this.viewer.canvas.onclick = evt => {
        this.getDbIdAtCoords(evt.clientX, evt.clientY);
    }