Cookie Encryption Issue

Nathan, i am talking about the data flow between F5 and backend server. In that data, i see sometimes the cookies are encrypted and at times it is not.

So wondering is this so ? Not checked on the client, but my first concern is when cookie encryption is set to required, shouldnt it always be encrypted :

ltm persistence cookie /Common/Persist_192.168.1.1_443 
{ app-service none 
**cookie-encryption required** 
cookie-encryption-passphrase $M$O0$PU5nvTKYL2GUTJInH7ZvSw== 
defaults-from /Common/cookie 
method insert 
timeout 180 
}