PNG textures render as solid black (embedded in WAD)
Pretty much what the subject states.
PNG flats render correctly, however PNG textures render solid black in game.
I attach a test wad for Heretic, that converts the entirety of the games textures, flats and also some of it's sprites (the sprites are present to test a bug with PNG sprites that is a separate report), to PNG.
I meant to report this at the same time I reported the above mentioned PNG sprite issue, but I forgot, my apologies.