I think I know what the cause of the sliders not showing up is. I’ve encountered this problem before, while working on something unrelated to the QRTEngine. It’s a Qualtrics bug, which they haven’t fixed yet, but one that can be worked around. Let me see if I can find my previous solution to the problem.
As for your other problem, I’ll need to write a small FAQ on that, as I’m pretty sure it’s going to be a common problem. The fix would be to add your own button (in the HTML) and then, upon clicking, call the function QRTE.proceed() to proceed to the next stimulus.
In fact, I’ll write a FAQ entry for both, hang on!