Thanks Mike, I think I'll open a support call about it.
It's odd because I don't see any errors in Chrome and it looks as if it has posted a new record successfully:
addResults: [{objectId:571696, globalId:null, success:true}]
0: {objectId:571696, globalId:null, success:true}
globalId: null
objectId: 571696
success: true
deleteResults: []
updateResults: []
but then when you go to do an attribute update on the new record it gives you the response:
addResults: []
deleteResults: []
updateResults: [{objectId:571696, globalId:null, success:false,�?�}]
0: {objectId:571696, globalId:null, success:false,�?�}
error: {code:-1, description:Update for the object was not attempted. Object may not exist.}
code: -1
description: "Update for the object was not attempted. Object may not exist."
globalId: null
objectId: 571696
success: false