Lightboxes not working when invoked from modern player menu or hotspots alike.

I have a course with 3 lightboxes ('instructions', 'disclaimers' and 'credits'). The first one is invoked only by the Modern Player menu (a tag has been created ad-hoc for this), the second from two separated hotspots ('main cover' and 'contact' pages) and the third from a hotspot ('contact' page). None works and I cannot understand why. I cannot share the .story file publicly though. Any clue on possible reasons? I never had problems with any lightbox (hotspot or player menu) and used the same lightboxes in other courses.....just here I cannot see why they do not work. I can share the file with articulate support but thought that maybe someone has a clue on the case? Thanks in advance.