Hi Geoff,
Thank you very much! I was able to identify the issue, it was actually a yet unknown bug due to a wrong option check. I have corrected a single line of code within Ajax Search Pro to resolve this issue, now it should work fine.
Please make sure to copy the ajax-search-pro plugin directory from staging back to the production so the change is propagated.
I will make sure this issue is permanently resolved within the upcoming version.