How to handle difficult owners and resolve ongoing disputes effectively?

Unfortunately, that's a common situation. I suspect this is a small scheme. My experience is that with smaller schemes, you find much more of this sort of thing happening because there is a higher tendency for owners to be residents.

The first question is why do we think this is happening? What did/do they do for a living? The conflict may be due to the nature of the individual's job, which may be methodical and forensic in nature. If this is how they're approaching strata, strata doesn’t work that way. Does the owner have a valid point? It sounds like a few things are not going according to plan in this scheme. It may well be that one small thing is happening in the scheme and it's causing a problem for this owner.

By asking these types of exploratory questions, you get down to the nuts and bolts of the situation. It is important to consider whether the individual is fulfilling their responsibilities appropriately, and if not, to address the specific problems and work towards resolving them. Facilitate a discussion addressing specific issues rather than just having a general chat.