Are you double-clicking post? Created an issue in the PWA web app because latency there made me do the same.
Discussion
Yes, but now i learned i need to hit post and then refresh the page.
I click once and wait until I see the "Message successfully noted" toast. Apps that have a lot of background overhead need to have some kind of indicator of readiness. There hasn't been any response to my issue or others so I don't think the PWA is a priority.