Affected police which is marked for retirement, throws error when trying to edit

Following the AWS mail that policies that are using retired policies to be modified to use fine grained actions, Our account had 2 policies that are not due for modification and out of 2 I was able to modify only one. The policy named AwsSSOOnlinePolicy (not sure it is AWS default policy type) is listed under "Manage New IAM Actions" with "aws-portal:ModifyAccount" as Deprecated IAM actions, but when trying to edit shown with no JSON content ot policy does not exist.