Here is the log and example for CreateMatchmakingTicket. Execution to right leads directly into the CreateMatchmakingTicket node. I get similar errors trying to create / use an entitykey for SetObjects as well.
LogPlayFab: Request: { "Creator": { "Entity": { "Id": "1234123412341234", "Type": "title_player_account", "TypeString": "title_player_account" } }, "GiveUpAfterSeconds": 120, "MembersToMatchWith": [ { } ], "QueueName": "Just_Two" } LogPlayFab: Response : {"code":400,"status":"BadRequest","error":"InvalidParams","errorCode":1000,"errorMessage":"Invalid input parameters","errorDetails":{"EntityKey":["Type or TypeString is required.","Id is required."," is not an allowed value of Type."]}} LogBlueprintUserMessages: [None] PlayFab : Create Matchmaking Ticket - FAIL >>{ "errorcode": 1000, "errordetails": "EntityKey: Type or TypeString is required.\nEntityKey: Id is required.\nEntityKey: is not an allowed value of Type.", "errormessage": "Invalid input parameters", "errorname": "InvalidParams", "haserror": true }