I am having nearly the exact same issues as this question. However, in this instance I have already added the Jira Server app to the channel:

And I have configured the project ("Automations") to post to this channel:

And have the Advanced Setting for previews turned on:

But I'm still running into the problem where no issues are being previewed:

Is there other troubleshooting I should try or another reason why this wouldn't be working? Thanks!
cc: @Daniel Eads I saw you were helpful in the other post and wondering if you could help me out.