thank you for your patience. I believe I have now implemented a solution to the STOP button issue which you reported.
This solution is hopefully more robust than the previous functionality. It should not interfere with the HotPot's "delay3" setting (= time delay at the end of the quiz). At the same time, it will allow the results to be saved if students navigate away from the page.
I tested the new functionality in JCloze, JCross, JMatch, JMix and JQuiz, in all combinations of STOP button, and Delay3, and a number of different output formats.
Please be aware that I have not tested yet in Rhubarb and Sequitur. If you could send any feedback on those two type of exercise, with and without STOP button, I would be most grateful.