XB1: Must relog to allow hydrogen to properly flow from one tank to another
1. get a large hydrogen tank
2. Fill hydrogen tank A so it has a percentage above 0
3. Set hydrogen tank A to stockpile off
4. Build a second hydrogen tank.
(Connect the two tanks via conveyor system or directly attached)
5. Set hydrogen tank B to stockpile on
Marvel as hydrogen is not drained from A into B.
Go back to main menu and reload. Presto, hydrogen moves.
I understand this to have been a reported bug on pc as well.