Obsidian: notes start as blank

Are you using iCloud?

Then, perhaps this is the solution for you,

open Finder, navigate to the parent folder of your Obsidian vault folder(s)

Click on the cloud icon to the right of Obsidian. In my screenshot, the cloud icon does not show anymore as I already did it. Doing this tells iCloud to always keep local copies of the file. Else, it only downloads on-demand, which is why there is always a lag for some of you.