On a build only contract, a Contractor has no contractual design responsibilities. This is also an Option A lump sum contract.
If you are issued designs at the start of the project, but find missing information on it a time-period (months) down the line, where do you stand contractually?
If a Technical Query (TQ) stems from missing/ incomplete design information, but you raise it late in the project - is it still a design related issue? If this drives out your critical path - is it concurrent (should have raised TQ earlier) or does it sit with the design (given that it is not useable to build the works)?
Morally, I appreciate you should raise issues as soon as possible - to mitigate delay. However, is this the same contractually? Of course, NEC does not recognise TQ’s, but in terms of risk management… where do you stand contractually?