Thanks for the quick reply @qtwrk.
As far as I know, all of the caching features of A2 Optimized are provided by LSCWP so any changes I’ve been making were done in the LSCWP options and didn’t think to look in the A2 settings… which I’ve done now.
I’ve found a setting in A2 that would dequeue WooCommerce Cart Fragments and AJAX calls on the homepage.
Turned that off and all is well. (It’s okay to point and laugh)
Thanks again for your time