Issue with Firefox: Could excluding slides from the completion record work? If so, how to do this?

 Dear Community,

We are using Storyline 3 (Update 12: 3.12.24693.0) to create courses for a bullying prevention program in schools. These courses are provided to schools by Moodle 3.11. Our courses consist of content slides (e.g. 20) and slides that are only shown as lightboxes (e.g. 5). For the completion of the course, users only need to visit the content slides (the lightbox slides are optional).

I tried the following: When publishing the course, I selected e.g. “Track by number of slides viewed: 15 out of 20”. Then I would upload the course to Moodle. But if I go through a course and click “back” on one of the last couple of slides, these slides would turn green (one of the background colors we are using) and my cursor would turn into a “loading” icon and I am not able to proceed. Interestingly, this only happens when I use Firefox, but not with Google Chrome, Microsoft Edge, Safari. However, since Firefox is a very common browser, I have to find a way to fix this.

As this issue only appears for the last couple of slides, I assume it may have something to do with the tracking setting (e.g. “15 out of 20”). One solution I see is to tell Storyline, which slides specifically have to be visited to complete the course (so, e.g. to visit the 20 content slides). I found this comment in the forum (https://community.articulate.com/discussions/articulate-storyline/completion-by-number-of-slides-viewed#162020): “You cannot exclude slides from the completion record unfortunately but that would be a great feature.” But this was almost 9 years ago, so I was wondering, if there is a way to do it by now.

Can anyone help me with this problem by any chance? I would be extremely grateful for any kind of support or hint on what to try. If you need any further information, just let me know.

Many thanks in advance and all the best
Franziska