Hi Dietrich,
It seems like we are not able to replicate this issue locally as the announcement get posted correctly without any error. May I know the exact details on how you would normally post the announcements on your site? If possible kindly provide us with the screenshot of the error so that we can get a rough idea on how to reproduce the error.
You can also set up a test site and provide us with the access so we can directly debug the issue first hand.
Looking forward to your response!