That's not rendering the patch at all it seems, almost like the culling has decided it isn't visible

I've not been able to repro' this with some quick local testing around Pallas or Thebe. I also tried with the supplied savegame.

@SomenameIchose what GPU do you have?

I've not been able to repro' this with some quick local testing around Pallas or Thebe. I also tried with the supplied savegame.

@SomenameIchose what GPU do you have?
Intel(R) Pentium(R) Gold G5420 CPU @ 3.80GHz 3.79 GHz

I gave an another try to fly to Pallas but textures don't disappear this time. Maybe it happens at certain coordinates?

Yes, I tested it, they disappear at coordinates of S029°25'12 E042°42'07

I can reproduce, see the attached save file. Just load it in Pioneer and you should see it.

Jameson2.zip

Note that it happens both on my integrated Intel card and my discrete Nvidia card (with Nouveau).

This isn't a GPU/driver bug, this is CPU side terrain generation and the rendering calls itself. Can confirm that it's CPU side only so you'll see it on anything that can run it.

I can confirm that it's the Horizon Culling optimisation which is... over optimising for some reason 🤷 however nothing appears to have changed in the SSphere::HorizonCulling method in years. The only change I can see is to the centroid in GeoPatch but I don't know how that might be affecting it.

Oof nope that ain't it either, you have found me a real doozy of a bug 🤣

Ok, I might have a fix for this in the works but it's after midnight, so I'll continue another day

I've put in a first draft of a fix in #5829 which will need some serious testing.