HTML5 and Quiz issue

I decided to give Articulate one last try before moving to Captivate 9 to alleviate playback issues on mobile devices (HTML5). I wracked (wrecked) by brain trying to figure out what the playability issue is. When viewed on my iPhone 6 or my daughter’s Android smartphone, it seemed the video either wouldn’t play or took an extraordinarily long time to load. I went back this morning and recompressed the video to as small a file as possible without severely degrading the quality, and then replaced the old video with the new, then republished the file. It seems to have worked. 

I also tested the project on both my iPhone and my daughter’s Android phone. Both played the video! So - it looks like it works. The weird thing is the quiz loads but when an answer is selected, it stops without a correct or incorrect response. You can go to the next slide via the table of contents but each subsequent slide responds the same way. Is this because when compiled for HTML5, the quiz requires interaction with SCORM 1.2. 

BTW, the client's LMS (JoomlaLMS) doesn't currently support "Tin Can" so the project was published using SCORM 1.2 rather than Tin Can.

 So I guess my big question is why does the quiz misbehave on mobile devices but plays correctly on desktop/laptop devices? Hope you can offer some helpful tips or suggestions.

Eric