After lots of testing today there is still an issue when using the filtering.
It seems to be when changing the ordering via the S&F filter and also if stacking multiple queries up (for example, ‘free’ then ‘construction kits’.
This is very frustrating. I’ve spent so much time on this now.
There is literally one page, with one instance of S&F and I’m getting consistent errors with the infinite scroll and double loading.
I have disabled all plugins except S&F + Woocommerce, still occurs. Changed theme to default, still occurs.
I can’t think of anything that would be causing this issue other than a problem in the S&F plugin. Seems to me after following all setup instructions and testing everything within the plugin settings the basic functionality of infinite scroll is broken.