I am also having this issue on a convert world played as a realm, mob spawner works then the icon disappears and no mobs will spawn but there are flames
So far it appears not to be an issue anymore!!
This is a new world, no realm.
No, I am not on peaceful, one which will spawn and only one which
I also have this issue on XBOX ONE, I find that copying a world reverts your save game to a previous state as well as "Save and quit" I seem to be able so far to get around this by not saving at all and not even exiting minecraft but by closing it with another xbox game
I agree with the above. I purchased the Apple TV version specifically because it was announced that it would have the Better Together Update.