Pursuant to clause 13.7 whereas a notification which the Contract requires is communicated separate from other communications, and in relation to 64.4 whereas a Compensation Event is not assessed in the time allowed, the Contractor may notify the Project Manager of his failure.
Would the notification be deemed as a early warning or any form of written communication clause 13.1
With contractual communications it is good practice to refer to the relevant clause under which you are communicating, failure to do so risks the communication being found to be ineffective.
An early warning notification is communicated under clause 16.1 and this should be separate from any other notification so you need another notification communicated under clause 64.4 to notify the PM that they did not assess a CE within the time allowed. This notification is a condition precedent so no notification = no deemed acceptance.