Seems like a bug, filed an issue: https://github.com/FusionAuth/fusionauth-issues/issues/1503
Thanks for the additional information! It sounds like this is already an active issue that you can upvote for consideration into future versions of FusionAuth.
If a good workaround comes to mind, I will be sure to let you know.
Disable the application configuration for this webhook. That is not doing what you think - it is a legacy configuration that causes some confusion.