Convoy bug? [BE]

I noticed this during a game I had going for a while. Thought it may have been an issue with playing a save file after the last update. However, in a new game, it appeared when I tried to connect my first trade route. Any ideas what the text means in the image attached?

Think I discovered the issue, unless some game mechanic unlocked convoys suddenly, related to a broke mod - Previous Route in Red (v.1). Unsubscribed to it and can now select trade routes.