The command /gamerule doimmediaterespawn false doesn't work on BDS software
Toggling the gamerule on seems to work perfectly (/gamerule doimmediaterespawn true), but then you cannot turn it back off using (/gamerule doimmediaterespawn false). 

However the commands both work correctly on normal worlds, so it seems to be a BDS issue.

Steps to reproduce:

1. Start and join the BDS server with a cheats activated world.
2. Give yourself op through the console.
3. Open the chat and do the /gamerule doimmediaterespawn true command and notice that the immediate respawn switch toggles on in the "Game" tab of the settings menu.
4. Kill yourself and see that the immediate respawn gamerule is really set to true.
5. Open the chat again and do the /gamerule doimmediaterespawn false command and notice that the immediate respawn switch is still toggled on in the "Game" tab of the settings menu.
6. Kill yourself and see that the immediate respawn gamerule is still set to true.

Expected results: The gamerule doimmediaterespawn is set to false after running the /gamerule doimmediaterespawn false command.
Actual results: The gamerule doimmediaterespawn is still set to true after running the /gamerule doimmediaterespawn false command.