I have noticed an unexpected behaviour in Network Analyst (NA) Service Area Polygon function.The attached image shows the service area polygons at some arbitrary network distances from the highlighted facility. The distances are listed in the Breaks_NDist field values in the "Properties-Facilities" dialog box. As you can see there are 7 breaks. However, if you see the list of polygons, there are only six service area polygons generated by the NA. You will also notice that the polygon for the distance 131.18 ft is a very thin donut shape polygon unlike the others which are desired disc-shape i.e. no holes.
Curiously, the extent of the final polygon does reach to the final break distance i.e. 198.17ft in some directions along the network. Also, this happens to only some of the facilities.
Would anyone happen to know of the reasons for this behaviour, and way to solve this.
Thanks a lot.