Congratulations to all of the staff members who got promoted/all the new staff members, big congrats to @KathrynsWill @rangedhealer77 and @Tylewr for (SOTM)!
As Tasses mentioned above the website does work quite well on mobile and I've seen this issue talked about for quite a while now. I do feel that it would be handy for a ManaCube app but I don't think that's what ManaCube is focusing on right now, possibly in the future.
Change your Minecraft version to the recommended version for Survival: 1.13.2. That should fix your issue, the ground glitch usually only happens on versions higher than 1.13.2
As Raptor has mentioned the spawner might have stacked with another nearby or possibly might have fallen into your happens, not sure, guess you'll need to wait for Gapple to check.