Hello, I’m having the exact same problem. It happened after I upgraded to 2.82 but not right away. All was well for several days and then it just stopped working correctly. I was thinking it was a plugin but I tried to disable them with no luck.
It’s a strange problem because you would think a post will either work or not. If it doesn’t post the first time what makes it post on the second try from the saved Draft? It doesn’t seem to be a permissions issue because then it would never Post at all. It may be some kind of bug but re-installing WP 2.82 + my theme doesn’t help either.
I’m stuck…