I have a stock 500GB internal drive and a USB3 500GB drive one my Xbox One.

Until this week they showed as a combined available/used space in the apps dashboard and games where automatically installed across both drives, this has now stopped and the drive are displayed as individual drives.

Has anyone else come across this issue? I've searched a few forums with no hits.

Cheers Tim.

BTW I've already switched the unit off and on and disconnected the drive and reattached.

I am not having this issue. It breaks it down by device in my Storage tab under settings, but in the apps & games window it combines the two. Make sure the storage device dropdown there is set to "all" on the top of the screen.