API Shield JWT validation not working

I am attempting to configure JWT validation via API Shield, the JWT tokens are being generated by AWS Cognito and the JWK values have been entered into API Shield

However when I require a valid token Cloudflare rejects the token, but the token is valid if the same values are entered into other tools (token.dev etc)

I have also then manually created a JWK+JWT with matching parameters and entered these, and they are accepted by API Shield as valid

How can I further troubleshoot why API Shield is not happy with the very valid JWT/JWK from AWS Cognito?
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