Hi Max Lock,
We have tried to replicate the issue in our latest version ( v26.2.14 ) and in that we could not find any NullReferenceException on using EnforceProtectionAsync API. We request you to upgrade to the latest version ( v26.2.14 ) and try on your end.
If the issue still arises in the latest version, it will be more helpful for us if you can share the issue reproducing sample so that we can validate it further and provide with the necessary solution.
Regards,
Suresh I