I have API gateway set up in account A and I have linked my lambda in account B with my api method in account A (added the correct permissions to account B). It always used to worked perfectly.
Now when I tried to deploy a change to the api gateway it keeps saying "The policy of Lambda function must explicitly authorize the method or custom authorizer with a SourceArn condition for cross account integration".
I have checked multiple times, all the permission are there in account B on the lambda function. I even deleted them and added them again. If I add the permission for just the lambda function without the alias it works, but when I add my alias then I get the "The policy of Lambda function must explicitly authorize the method or custom authorizer with a SourceArn condition for cross account integration" error, but I can see the permissions for my lambda with the alias in account B.
What am I doing wrong?