Procedural mesh generation system creating artifacts

[digital cairn]

I'm trying to write a mesh generation system for a chunked voxel world, however, I'm experiencing weird artifacting that I can't track down the source of. I've attached some images to give you an idea of what this looks like.

I've tried several things, and I believe I've tracked down the issue to the code that decides whether to create the faces for each side of a block or not.
Performing len() on the Vec storing my position values after a code modification setting every face to generate results in the following: 147456
This is exactly what my calculations say it should be, so I don't think there's a problem with that. I'm not experienced enough to say whether or not this is actually true, or if this is a purely visual issue.
I'm not even sure if this is really related to Bevy, other than it outputting to a Bevy result and being displayed by Bevy, however I'm hesitant to post this on the Rust discord since it may be unsuitable.

My generation code is all here: https://github.com/Veritius/rustcraft/blob/af5267372c983dcc81a5f403759fc719e9d14547/modlib/src/world/chunk/meshing/mod.rs
I'm aware my indentation practices among others aren't particularly good.

[cloud rampart]

on line 90 https://github.com/Veritius/rustcraft/blob/af5267372c983dcc81a5f403759fc719e9d14547/modlib/src/world/chunk/meshing/mod.rs#L90 you check the block above
this_block_pos + IVec3 { x: 0, y: 1, z: 0 }
but then add the front face

      POS_IDX_A, POS_IDX_E, POS_IDX_B,
      POS_IDX_E, POS_IDX_F, POS_IDX_B,
  ], offset));

and in your comment you say its the back face?

and on line 102 you say its the front face, but on 103 you check y-1, which is the bottom, and then add the back face HDC GHC

x goes from left (negative) to right (positive)
y goes from down(negative) to up (positive)
and z goes from back(negative) to forward/front(positive)

[digital cairn]

I'll have a look - I was wondering if I mistyped the coordinates. I'm more used to thinking in a Z-up pattern, for some reason.

I'll look more thoroughly through the selection code tomorrow, as it's midnight over here.

[digital cairn]

While my coordinates were incorrect, the anomalies remain. I'm really not sure what's happening here.

Notably, it only seems to happen when blocks are adjacent, and not just on chunk boundaries. Singular blocks work fine.