I been playing with Forge, Optifine, and a couple other harmless mods just to help me get around with some vanilla game play on servers.
Problem is when I was playing the latest versions of Forge for 1.14.4 today and then went for today's latest version for 1.14.4, I noticed that Forge seems to have a conflicting issue with Wynncraft's grass block texture making it the missing texture block. I removed all the mods and even tried it without Optifine only to get the same result. So I used the copied and renamed server's resource pack in my single player world just to get some screenshots (Had to crop a bit and lower res because the size was over the limit) and here are a couple, one with just playing with Optifine (normal grass) and one without any mods or Optifine and just Forge (With missing textures):
Note the fact the grass block in my hot bar is normal, but when I place it down it just still goes with missing textures...