Hi!
I think I found the main cause, and possible others as well.
1. The “select/deselect all” button you implemented on the top of the list is de-selecting everything, even the hidden elements of the form. It causes to not search within any post type, therefore it returns no product results.
I suggest adding a filter to the handler script to only select option, which are indeed terms, something like:
$(“.asp_option_cat .option checkbox”)…
or:
$(“.option:not(.hiddend) checkbox”)…
This will make sure to select only visible checkboxes, nothing else.
2. I’m not sure if you need product tags/categories as results. If not, I suggest de-selecting them on General Options -> Sources 2 panel: http://i.imgur.com/aonDQTy.png
3. The results override is not activated, therefore the results on the default wordpress results page are not overwritten by Ajax Search Pro. Here you can read on how to enable that. After enabling, the same results should start appearing on the default search results page.
I hope it helps!