Ribcage scenery item texture error

One side of the ribcage scenery item is normal, but the other side appears to have incorrectly mapped textures, so it ends up transparent on the outward-facing side of the model. This is hard to verbally explain, so here are some screenshots.

I am using test version 0.18.54 but the issue has existed since at least 0.18.38 (the earliest version i’ve played).