Ominous persisting rumbling sounds from the deep

I mostly play this game in Creative Mode, and I tend to use spectator to prebuild underground halls etc, before hollowing it all out.

At some point, this causes a weird rumbling sound in certain areas which seems to persist, no matter how much of the voxels I clear out. The sound itself could probably be best described as what I imagine an earthquake to sound like, like rocks grinding together. Once I move "out of range" of the source, the rumbling persists for a second or two before fading away. No abrupt end of the sound.

Below will be a link to a world of mine where 3 occurrences of it are nearby each other. Not sure how these things go on your end, but my compound is just east of the prebuilt Arena, almost impossible to miss. Fast traveling to Bar Hadur / (E,3) / (B,1) puts me at least in the middle of the inner gate.

One location is on the ground floor of the inner keep, when you're on the stairs.

Another is reached from the courtyard through a little side door near the tanning rack. Behind it are stairs going down, where the same rumble can be heard more or less halfway down.

The third spot is outside the outer castle gate, in the furthest room, ground floor, of the building with the wooden roof tiles. If you stand against the wall across the room, you should be able to hear the noise there as well.

It's a pretty niche issue, and so far it did happen when I dug something out -before- placing blocks, so I understand that it's probably not too important to fix. Here's reporting it anyway!

https://steamcommunity.com/workshop/filedetails/?id=1630957271