Completion trigger not reading

Hello everyone!

So, a bit of a tricky one, as I am not sure how to come to the core of the issue - any tricks on analysis, testing, or similar are welcome. I am working on a pretty complex course that I hope to complete soon. The issue comes with publishing and our LMS. First, our LMS is not SCORM compatible, and we have the Test as a separate section there. Therefore we have to trigger the transfer from the course (HTML) section to the Stage Check. Until recently, a line of JS worked fine. Then it stopped due to some browser updates and now we need to separate the triggers - first, complete the course then transfer. I made a few small files that worked fine there, but when I set the same parameters for publishing and tracking/reporting for the course that I am working on, it did not read the completion trigger. 

So, I have the confirmation that the completion (Complete course) trigger works fine on the LMS, but with the mentioned course, it simply does not. Could it be up to the size? complexity? place fo the trigger? Did anyone have any similar case? 

(Help!) Thanks in advance :D