You need to connected to the same relays to see the message. If the two clients are connected to different relays from each other then won’t be able to see it.
See pic below for visual explanation. 
Discussion
I'm aware. From I can tell though by alternating clients in this conversation, I can see posts from both from Primal and Amethyst just fine. It seems to be just that single post I made yesterday that is only shown on Primal.
You must be on the same relay for someone to receive your note.
You are not going to receive your note til you get relays on amethyst connected to the relays on primal account.