I can confirm your findings.
Because of this, this post would be better classified as a feature rather than a bug. There's an opportunity here to make it more clear that webhook messages need to be manually published. But also for ease of use, I think it would be even better for webhook messages to auto-publish.
I'm down for that. I'll flip this over to a feature request. If you wouldn't mind editing your post to reflect what we've found here that would be helpful!
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