Amazing, thanks Jory. You gave me an idea and I am simply excluding the specific URLs that seem to be affected, and that appears to be working.
I’d be interested in a more global solution – I use Lightspeed cache and couldn’t see any way to get it to disable caching when the hook ran. As I am not that technical I may be missing something obvious, but if you know off the top of your head hat I need to do that would be brilliant.
Thanks for your help!