Based on what I’m seeing with the first screenshot, the property is likely receiving raw text so it does not contain the formatting you would get with HTML included.
Are you able to confirm that the content being sent to this property from your external source contains HTML within it or if it is just raw text?
Hey, I would like to join the thread. Having a similar problem, I’d like to send Rich text via the API to input symbols and present them nicely visually for the salespeople.