Instance is not unique

SELF-SOLVED: Removed unique constraint on the allPlayers index

I get this error in PG:

  "errors": [
      "message": "Instance is not unique.",
      "extensions": {
        "code": "instance not unique"

re: this entry in the schema:

type Player 
 {  rankingid : String!
    uid : String! @unique
    rank : Int!
    challengerid : String

and this function in PG:

mutation CreateNewPlayer {
    rankingid: "280892229782864389"
    uid: "280689785097421325"
    rank: 2
    challengerid: ""
  ) {

the uid I have used here is unique, the rankingid is not.
I removed the @unique constraint that was previously on the rankingid in the schema and successfully uploaded it (checked).

  1. Why am I still getting the ‘Instance is not unique’ error?
  2. What else should I look into to resolve?
    thanks …