Expected Users array is null, despite being set on room creation.

Hello!
I have got my turn-based game saving and loading state data from Playfab pretty nicely now!
However when I create a room with type Load and pass it the following State data...

{
"ActorCounter": 1,
"ActorList": [
{
"ActorNr": 1,
"UserId": "59FCE1AD1A872162",
"Username": "",
"Binary": "RGIAAAEBRAAAAAFi/3MAAA==",
"DeactivationTime": "2017-11-08T03:36:51.4038169+00:00"
}
],
"MaxPlayers": 4,
"ExcludedActors": [],
"PublishUserId": true,
"ExpectedUsers": [
"59FCE1AD1A872162",
"A5F29DFD0274B092",
"453275C8340F5E91",
"39BEBAF8646A2B0F"
],
"RoomFlags": 9,
"Binary": {
"18": "RAAAAAVi+nkABHMABERlY2sABERpY2UACVN0YXRlTGlzdAAITW92ZUxpc3RzAAREaWNlcwAEaDAwMHMACE1vdmVMaXN0cwAXc3RhcnQsMC4wLjAuMzU0MzU1LjQwMzFzAAREZWNrcwA8ZXJoZzgwazZxbmw0MzFvYmRwaWNhamZzOTVtdDI3dlBETldPSUx1RXpCR0hBd01GVVJ5VnhKU1RLQ1FYcwAJU3RhdGVMaXN0cwAlMC5lcmguLjAwMDAuMy4wLDEuZXJoLjAwNDEwMy4wMDAwLjMuMQ=="
},
"CheckUserOnJoin": true,
"DeleteCacheOnLeave": false,
"EmptyRoomTTL": 12000,
"IsOpen": true,
"IsVisible": false,
"LobbyType": 0,
"LobbyProperties": [
"Deck",
"Dice",
"StateList",
"MoveList"
],
"PlayerTTL": -1,
"SuppressRoomEvents": false,
"Slice": 0,
"CustomProperties": {
"Deck": "erhg80k6qnl431obdpicajfs95mt27vPDNWOILuEzBGHAwMFURyVxJSTKCQX",
"Dice": "h000",
"StateList": "0.erh..0000.3.0,1.erh.004103.0000.3.1",
"MoveList": "start,0.0.0.354355.4031"
}
}

...if I join the room, and try to fetch it's properties, the returned ExpectedUsers array is null.

This is baffling, because the expected users array should be filled by the state data, and PublishUserId is set to true. Is there some flag I am missing? Do I need to expose ExpectedUsers in the LobbyProperties?

Does anyone have any idea what could be causing this?

Cheers,
Dan