Fog material turning invisible




Hey all, I’m trying to follow either of these two tutorials on making fog that I can attach to a single object (https://www.youtube.com/watch?v=IWGujvx6sSg - https://www.youtube.com/watch?app=desktop&v=ZOV_9P9V4Pw)
These videos make it seem pretty simple, but when I do the couple of steps to make either of the materials shown above, it causes any mesh to just turn invisible, rather than to display the fog shown in the videos? What am I missing? Is there another way to achieve what’s shown in these videos?