When playing the "Imp Springs" map of DUMP 1, I noticed that the normally translucent slimefall texture at the start of the map was instead a glaring opaque white. I checked r_drawtrans to make sure it was enabled, and it was. Fireball translucency and lost soul translucency are just fine, they work as intended. And in addition to this, I noticed that the texture was still displaying in a way (instead of some other means of corruption or error), as when I opened the main menu, the color overlay that displays when you open the main menu highlighted some dark spots in the animated slimefall texture.
Spoiler: In-game
Spoiler: Main MenuGPU is an NVIDIA GeForce GTX 1080 with pretty new drivers.
GZDoom version is 4.0.0. Hardware accelerated rendering is selected.
EDIT: some more screenshots in the map, to further show the weird rendering issue:
Spoiler: Lava pillars
Spoiler: Yet more lava pillarsIt's also worth noting that the translucent blood lake in the center of the map rendered and displayed just fine and as intended, which was a bit odd considering this was map geometry rather than an actor with translucent rendering applied to it.