I think I may have stumbled across an issue with Mathematica’s built-in ConcaveHullMesh function that doesn’t seem to arise with Jon McLoone's NonConvexHullMesh resource function. The issue is illustrated in the attached notebook. My guess is that it occurs when the point values are modestly large (fairly typical of cartographical coordinate systems) and/or the number of points exceeds some threshold (noting that the function works when I take a small sample from the point dataset).

From what I’m seeing, it looks like Jon's resource function may be more robust than the built-in function.

Any thoughts or solutions other than what I've already tried would be welcomed.

Many thanks,

Ian