If a Project Manager does not respond to Contractors early warnings nor attends the risk reduction meetings called by the Contractor what are the implications?
The implications are that the problem you raised as a potential problem (EW) is unlikely to be mitigated and is more likely to materialise into an actual problem. If this is something that is not the Contractor’s risk under the contract and is a reason why the Contractor can claim the resultant time and/or cost effects as a compensation event, the Employer will now be likely to be paying more for that event than they could of.
The Project Manager is there to act in the best interest of the Employer, and a key element of that should be to manage the early warning process effectively. I think the bottom line is all you can do as a Contractor is raise the issue and try to encourage the risk reduction meeting to take place. If they choose to ignore you there is not a whole lot you can do about it. The important bit however is that you can at least not be called to account.