After weeks of tryign to track down a bug - I've discovered that it's the Ezoic consent Management platform, that when I switch it on, it breaks Woo Commerse. The exact issue is that when a user comes through Consent Management (in particular a GDPR region - as I've tested this and the bug does not occur when accessing from a USA Location for example) - the user is not able to add a product to the basket.
When I disable the Ezoic Consent Managment platform, the issue goes away.
I am not able to diagnose the exact sequence of events.
Has anyone seen this before, or have a fix? If not, does anyone use a 3rd party consent management platform that works with Woo Commerce?