amplify post-confirmation cognito trigger not working

I can't believe how difficult this is. Following the official docs found here (https://docs.amplify.aws/guides/functions/cognito-trigger-lambda-dynamodb/q/platform/js/#create-the-lambda-function). Also reviewed some other community builder type posts...

Set up a lambda to write to an existing dynamodb table (set up in amplify graphql schema) which does not trigger. Also the docs do not make any mention of permissions. I tried without them and also by adding permissions to the lambda execution role in the specific lambda's foo-cloudformation-template.json. Since the lambda doesn't run, there are no logs to review.

Specific steps were:

1/ set up ddb table in graphql schema 2/ added lambda with access to dynamodb resources 3/ amplify push 4/ go to cognito, add post-confirmation trigger to above lambda 5/ test and fails 6/ visit lambda, no permissions to write to ddb table (none mentioned in docs but i have had to do using other lambdas with amplify) 7/ added resource permissions to write to ddb in cloudformation-template.json 8/ amplify push 9/ verified permissions exist as does the lambda invoke function from cognito. 10/ still fails

Have used node.js 18 and 16 versions. Other lambdas in my amplify app work fine connecting to backend resources.

Please advise. Thanks.

V.

Addendum: I have self-sign up turned off and am adding users in the cognito userl pools section but I don't see how that should make a difference as the user signs in successfully.