Unable to reset user password with woocmmerce. Reset link doesnt seem to work

Hi
When user requests a new password via
https://MYSITE/my-account/lost-password
they receive an email with a link to the lost-password page with a key appended like this
https://MYSITE/my-account/lost-password/?key=tyZLF3JYttOtscWcAerx&id=2

If they click this they are then redirected to
https://MYSITE/my-account/lost-password/?show-reset-form=true
which asks then to submit their user/email again and not reset their password.
And so are in an internal loop. And then lock out as inevitably they try more than once in 10 minutes

I am on wpengine and have disabled an overrides to woocommerce and my account page / email templates in my child theme

Any ideas on how to troubleshoot this?

Many thanks