Invisible Player and mobs (Minecraft 1.14.4)

On my friends computer, hes installed MCreator on it but weird stuff happen on it.

When he runs Minecraft on it, most of the time it says 'A crash in JVM native code was detected.' Even though it says don't worry, it continues to do it and if it does manage to load Minecraft, when he joins creates or joins a world it will either crash Minecraft or it will load the world but both his player and all other mobs in the game will be invisible. You can still see the shadows of them and still hear them but everything that is an entity is invisible. The only things you can see is if they are holding stuff like the skeleton with the bow or zombie with armor etc. 

Please help!

Thank You!