Requested ID not returned from GmsCore -- ERROR_INTERNAL

[stolk]

I do a Fetch on a player id, like so:

 game_services_->Players().Fetch( id, fetchcallback );

On one party, this works fine.
On the device of the other party, I get ERROR_INTERNAL as Fetch result.

In the logs I see:
Requested ID not returned from GmsCore
What could be the cause of this?

I/swaag   (19043): Our opponent in slot 0 has id 110078821488315885564
I/libjingle( 9661): IbbDataTask::ProcessStart() called:
I/libjingle( 9661): Got Xmpp data back: <ibb:data ibb:seq="1" ibb:sid="0" xmlns:ibb="http://jabber.org/protocol/ibb"/>
I/libjingle( 9661): static void gtalk::LibjingleJniHelper::DispatchIbbSendResult(jobject, const string&, const string&, bool): Dispatch ID:1
I/libjingle( 9661): IbbDataTask::ProcessStart() called:
E/GamesNativeSDK(19043): Requested ID not returned from GmsCore.
E/swaag   (19043): Players().Fetch() failed for slot 0, id 110078821488315885564
E/swaag   (19043): Status ERROR_INTERNAL