NEC ECC: What next if PM rejects a notified CE?

What happens when a Contractor notifies a Compensation Event that he believes is an Event, but the Employer / Project Manager rejects this stating that in their opinion its not a CE, what is the next course of action and is the Contractor time barred on disputing the PM’s decision?

In terms of explicit procedures in the contract, the next course of action is adjudication which, under W2, there is no time bar.

However, implied within the contract - as there is a compensation event for it - is the ability of the PM and Supervisor to change their mind. Consequently, I would find out what the difference of opinion wrt why it is/isn’t a compensation event and then address the difference in the hope of changing the PM’s decision.