Nobody has responded to my early warning
Contractor side: Early warnings
Where the contract stands
Call a meeting. Under 15.2 either side can instruct the other to attend, which is a stronger step than a further e-mail (16.2 in NEC3, where it is a risk reduction meeting). Silence on a warning is not a compensation event by itself, and it does not stop the time bar if the matter is one. Your warning does protect you against a later statement under 61.5 on that matter.
Read the guide: PM ignored an early warning
This is our plain-English summary, not legal advice. Your own contract, including any Z clauses, decides.
In Contract Status, step by step
Check it on the record
The record shows whether a reply has come, when it was due, and that it is waiting for the Project Manager.

EW-0004 from the contractor side.
Ask for the meeting
On the Early Warning Register page, choose Request an early warning meeting: when, where, who and which early warnings. The page also shows the risk score, latest decision and open actions for each warning.

Risk Register on an NEC3 contract, in the same layout.
Record what was decided
The meeting has its own record: attendees, agenda, notes, decisions and actions, each with an owner and a date.

EWM-0002: asked for by the contractor, register issued by the Client side.
All screens are from the upgraded app, using a fictional water company, Kestrel Valley Water, and its made-up contractors.
What happens next on the other side
The Client side issues the revised register, which waits on its Action List until it is done. Each action shows on its owner's Action List until it is marked done. Under NEC4 the revised register is due within a week of the meeting.
See it on a contract you can click through
The guided tour lets you walk the same fictional account yourself. Or book a demo, and bring the situation you are dealing with.