Odd flowline behavior?

I’m working on an initial supercontinent split, and I think my flowlines are behaving strangely. If I remove all of the timesteps, I can see points that could be the mid-ocean ridge, but when I add the times I only get lines directly from the rift I originally copied the geometry of to create the flowline feature. They also don’t seem to end on the edge of the continent.

I’ve made sure that my Plate IDs and valid time are set correctly. I’ve tried removing the times and entering them again, deleting the flowline feature and creating it again from the rift, and even reset and changed the rotation of the two continents to see if the behavior will change. I’ve also closed and reopened the project, cleared the session, and opened and closed GPlates.

I may just be doing something wrong or I’ve overlooked something very simple, but any and all help is appreciated. Thank you.