If the OP has demonstrated to the Loss Adjuster that there is a direct relationship between an escape of water at the property and movement and subsequent damage of the house then, on the basis that there is no policy exclusion and no restriction in cover, the Loss Adjuster should and would be advising the Insurers that a policy liability arises and payment is warranted.
If this has not happened on this occasion, then there is a reason as to why the Loss Adjuster is not instructing insurers to accept liability. It is of no relevance whatsoever that other houses in the area have had problems. Each claim is treated on its merits and insurers will not accept that because there is a problem in the area, that this property automatically has the same problem. Also, in my professional experience, cracks from subsidence are plain to see, and are very obvious. I would be concerned that the Adjuster seems to have a problem seeing them. Either he/she chose not to see them ( which i would find extraordinary), or they are not readily identifiable.
If the OP has identified and proved that there is a clear connection between an escape of water and damage to the property, then i would suggest that the OP ask for the matter to be signed off by insurers and instruct that the case be referred to the insurance ombudsman for a ruling.
I would also advise that these types of claims are very difficult from both sides. It is often the case that extensive investigations need to be carried out, including cctv surveys of drains, probe holes to expose leaking pipes and allow examination of foundations, engineering analysis of the loadbearing capacity of the subsoil beneath the foundations to name but a few. It is not sufficient from insurers perspective for a "subsidence expert" to say that this should be covered by a policy, without proving that this is the case( obviously i don't know if this in the case in this matter, but i do believe that if the case had been proven, insurers would be paying this claim). Also, the policyholder has a duty to maintain their property, otherwise, insurers will place restrictions on cover or withdraw cover completely.