Bug: Updating the Thank You message makes it blank

I’ve updated the Thank you message setting to just say “Thanks!” but now the confirmation at the bottom of the page is just blank. The colored line shows up that’s supposed to say Thanks! but there’s no text. I looked at the HTML, and the <p> tag is blank.

Here are my current settings: https://i.imgur.com/cUenquy.png

https://www.ads-software.com/extend/plugins/error-notification/