Weird implicit search failure with Shapeless At and Nat._0

TableExample.scala

package shapeless.examples

import shapeless._
import nat._
import ops.hlist._

object TableExample {

  final case class Row[L <: HList](cells: L)

  final case class Table[L <: HList](rows: L) {
    def row[R <: HList](rowNumber: Nat)(implicit atR: At.Aux[L, rowNumber.N, Row[R]]): Row[R] =
      atR(rows)
  }

  val test = Table(
    Row(1 :: 2 :: 3 :: HNil) ::
    Row(4 :: 5 :: 6 :: HNil) ::
    Row(7 :: 8 :: 9 :: HNil) ::
    HNil)

  test.row(1) // Row(4 :: 5 :: 6 :: HNil) 
  test.row(2) // Row(7 :: 8 :: 9 :: HNil)

  // all of these below fail to compile with errors like:
  // could not find implicit value for parameter atR: shapeless.ops.hlist.At.Aux[shapeless.::[shapeless.examples.TableExample.Row[shapeless.::[Int,shapeless.::[Int,shapeless.::[Int,shapeless.HNil]]]],shapeless.::[shapeless.examples.TableExample.Row[shapeless.::[Int,shapeless.::[Int,shapeless.::[Int,shapeless.HNil]]]],shapeless.::[shapeless.examples.TableExample.Row[shapeless.::[Int,shapeless.::[Int,shapeless.::[Int,shapeless.HNil]]]],shapeless.HNil]]],nat_$macro$3.N,shapeless.examples.TableExample.Row[R]]

  //test.row(0)
  //test.row(Nat(0))
  //test.row(Nat._0)
}

It looks like it works if I change row to:

    def row(rowNumber: Nat)(implicit atR: At[L, rowNumber.N]): atR.Out =
      atR(rows)

But this doesn't work when I need to go through a chain of ops with At being the first one.