From Basic examples 3 :

  gr=Graph[{1, 2, 3, 4, 5, 6}, {Null, SparseArray[Automatic, {6, 6}, 0, 
       {1, {{0, 2, 4, 6, 8, 10, 12}, {{2}, {6}, {1}, {3}, {2}, {4}, {3}, {5}, {4}, {6}, {1}, {5}}}, Pattern}]}, 
     {FormatType -> TraditionalForm, ImageSize -> {85.859375, Automatic}}]

ResourceFunction["GraphNeighborhoodVolumes"][gr,All,2]

Limiting the radius to 2 as no effect on result after evaluation in my desktop (Win10):

<|1 -> {1, 3, 5, 6}, 2 -> {1, 3, 5, 6}, 3 -> {1, 3, 5, 6}, 
 4 -> {1, 3, 5, 6}, 5 -> {1, 3, 5, 6}, 6 -> {1, 3, 5, 6}|>.

This problem persist on other Graph's also.