/eth/v1/validator/duties/sync/ not returning sync committee data

[mcdee]

🐞 Bug Report

Description

/eth/v1/validator/duties/sync/<epoch> is not returning data about sync committee membership.

Has this worked before in a previous version?

No.

🔬 Minimal Reproduction

curl -s -H 'Content-type: application/json' --data '["71042","1"]' http://localhost:3501/eth/v1/validator/duties/sync/44504  | jq .

🔥 Error

{
  "data": [
    {
      "pubkey": "0xb88260f48d2d10d5f0ece23dcf05318804522740023c7f3948ec9a97159a1d0dcbb24590a42563b423ae9bea96525a05",
      "validator_index": "71042",
      "validator_sync_committee_indices": []
    },
    {
      "pubkey": "0xaffc434cf8138634a4cd0ef6cb815febd3db25760b1b6c522f9b4aa78e599b60336d7dd2e953192e45d4ac91f66f0723",
      "validator_index": "1",
      "validator_sync_committee_indices": []
    }
  ]
}

There are two errors here:

• validator index 1 does not have a sync committee membership in the given period. As such, no data at all should be returned for it
• validator index 71042 does have a sync committee membership in the given period. As such, its index should show up in the validator_sync_committee_indices field.

So the output should be

{
  "data": [
    {
      "pubkey": "0xb88260f48d2d10d5f0ece23dcf05318804522740023c7f3948ec9a97159a1d0dcbb24590a42563b423ae9bea96525a05",
      "validator_index": "71042",
      "validator_sync_committee_indices": [
        "1"
      ]
    }
  ]
}

🌍 Your Environment

develop on prater.