Several (most) boss enemies such as King Shaleback (King Kappa) and Thunderfoot are invisible.
Approach pretty much any of the boss enemies and you only see the “Skull” icon and possibly eyes.
Edited for clarity and spelling
Nearly similar issue as me. I created a post and explained how I was taming a shaleback until I got a greater variant, it was invisible and I placed it down, annoyed me cause I couldn’t see it so I left and tried rejoining and anytime I try rejoining my server it crashes my game.
The truly sad thing is, I have been consistently experiencing this issue since around the drop of Age of Sorcery. I typically reinstall the game after any updates/releases and see if the issue has been fixed, but so far it persists. This is unfortunate as I could truly see me heavily investing in this game with all dlcs, the battle pass, server rental, and even streaming it; however, in light of this persistent issue I can not in good faith even recommend playing the game at all.
Yeah, as we speak I’m currently redownloading and will see if anything changes. Hopefully things on your end go better. 
Redownloaded and tried again, nothing. RIP.
Invisible boss enemies, sometimes invisible enemies in general. My camel is always invisible except you can see its lips and eyes floating. Invisible background items on occasion. Uninstalling and reinstalling does not help. I have played for several years and was streaming playing this almost daily until the last big update, now its too frustrating. Dont forget the continual crashing of the game
Well Its almost October now and this issue still persists…and now i have areas of the map that the terrain is missing and all the builds are just floating in the sky… if you try and get to them you enter a infinite fall loop… idk what they are doing but its not helping.