Riak 2.0.x Link Walking Returns Only Some Data

I was using riak 2.0.2, and I didn't understand anything.

A bucket named bucket contains an object whose key is key, from which 26 links were added to the elements of another bucket.

 curl-v-X GET http://riak-host.hoge.com:8098/buckets/bucket/keys/key

When I sent such a request, I was able to confirm that there are 26 links in the response header Link. However, when I did Link Walking in the following request, I received only 20 pieces of data.

 curl-v-X GET http://riak-host.hoge.com:8098/buckets/bucket/keys/key/targetbucket,_,1

I thought the linked object might not exist, so I checked it, but it did exist. What are the possible causes of this situation?