When editing the JWT Claim Check policy it displays under RULES:
Unsupported field schema for field root_rules_0: Unknown field type undefined.
and a json schema. See screenshot attached.
// dev notes
might be caused by https://github.com/3scale/porta/pull/1194 as this looks just fine: json-schema
Also make sure the correct version is installed in production. It's supposed to be 1.3.0 as it was fixed in the aforementioned PR.