Layered slide with audio locking up

I have a course that was created in SL2 in 2017. It contains a handful of slides that have a base layer with audio, and additional layers, also containing audio, all of which had to be listened to before the slide could be advanced. 

We had a number of learners somehow lock up the slide (I *think* from clicking too fast between the tabs, so the audio wouldn't complete). The settings were updated to allow learners to progress with only having to listen to the initial audio, however we continue to have folks who experience it on one slide. For better or worse, this only occurs in certain circumstances, so it is hard to duplicate to officially confirm how or when it is occurring, and as best I can tell, it is OS and browser agnostic.

On top of all this, we have a Spanish version that was translated from the problematic English one and that course has not generated the same issue, despite the triggers being the same on both files. 

Can anyone think of why it may still be tripping up? It is only on one slide, 5.20. Both files are attached for reference.