Description
A region that extends outside the analysis extent or overlaps NoData areas can cause the region to be split into disconnected pieces, preventing interior connections from being made. Interior connections for regions can only be completed within the analysis extent. Any NoData cells within the analysis extent will be treated as barriers when creating connections between regions.
Solution
Ensure that no region is split into disconnected pieces, either because it is located outside the extent of the input cost surface or where the cost surface is NoData.