I'm not sure which setting in Optifine causes it, but it looks like the photo below. I tried removing Optifine and it went back to normal, so I can be sure Optifine is indeed the cause.

It seems to be more of an Optifine issue, but they already have an open issue with modded model bugs. Wondering if there's a fix to be implemented in Totemic?

Not sure if I will ever get around to redoing the model myself, given that I'm not proficient at 3D modeling.

Afaik that is an optifine issue, and is prevalent with most mods.
Unfortunately, it just simply messes with the rendering system of most mods.

It's not helping that the Tipi model's topology is quite terrible. I was planning on redoing it at some point.

As of 3/1/20 is this still an ongoing issue?

Yes, this is still an issue

Yes, this is still an issue