If kes fails to deploy stack, the last resort is to directly edit cloudformation.yml and nested stacks like CumulusApiV1.yml.
For Cumulus 1.11, removing the following line worked:
ApiEndpointsLogGroup:
Type: AWS::Logs::LogGroup
Properties:
LogGroupName: '/aws/lambda/sdt-cumulus-ApiEndpoints'
RetentionInDays: 30