Why are question pools not working in HTML5?

I had a similar problem with a project that included question pools while using Captivate 2019 11.5.0.476.

The issue I had was that although the HTML5 course would open and play first time, if you closed the course then tried to reopened it would not play (continuous timer symbol). Different browsers produced the same issue. If the user was deleted from the course roster (reset), they could then open it again and complete the course as long as they did the course in one go. I narrowed this issue down to only when published as HTML5. I also found that if I replaced the question pool with fixed questions the problem was also resolved. 

After speaking to Adobe and updating to 2019 11.5.1.499, republishing the content has resolved this issue so I can now use the question pool in HTML5. Adobe support did mention that the latest update makes the HTML5 format more robust to potential issues related to browsers opening the HTML5 content.

As the others have indicated, the bottom line here is to make sure you have the latest verison and update.

Lieve is correct. Ideally you would want to upgrade to 2019. At the very least you should make sure you update your version to the most up to date version of Captivate 9 which I believe was version 9.0.2.437.

Of course CP9 is bit old now, the HTML output has been improved a lot with 10, 11 and 11.5. However I don't remember issues in CP9 with question pools. Can you check the exact version number under Help, About Captivate?