Will Abner

Yeah, agreed, we still have the issue as well. I have recently built two spawners and left a single block directly below the spawner and both of these spawners have stayed live for the past few weeks. I'm not sure if this is related or the game has simply become more stable with recent updates. You could always try that as well, and see if you see a difference.

Unfortunately taking the realm offline and re-uploading did not resolve it. I even tested the world when it downloaded locally, and the mob spawners would still not spawn.

I've been having this happen too, and wanted to provide some additional information. We are playing on our realm and have built several mob traps around monster spawners. The mob traps function like normal at first, but usually within an hour or so of completing them, we notice there is no longer a monster spinning inside the spawner. Usually mobs will still spawn even when this is the case, however after we leave the area and come back the mob spawner will no longer spawn any mobs at all. I have tested this with 3 skeleton mob spawners and 2 blaze spawners in the nether, all exhibit the same behavior.

We have tried switching to peaceful and back to normal, saving and downloading the realm and then re-uploading, fully lighting the surrounding area, etc.

Let me know if you need any more info.