All Lamda Function Test's Fail - Unexpected token '<', "<!--# Id: "

Hi,

Whatever I enter in Lambda as code (Python 3.9) or event json I get the same error. See below.

"Calling the invoke API action failed with this message: Unexpected token '<', "<!--# Id: "... is not valid JSON Deserialization error: to see the raw response, inspect the hidden field {error}.$response on this object."

I have tried following tutorials for very basic Lambdas and all have failed in the same way. Existing Lamda's built via a 3rd party CloudFormation integration also give the same result.

Any ideas what may be wrong?

Thanks