Just a random thought...

According to Wikipedia to circumference of the Earth at the equator is 40,075km. If you are not at the exact start location of the course it could be the Edge telling you how far it is to the start by going all the way round the planet.

As to why it is doing that, I don't know.

Is it always the same course? If the problem is with the course itself then it would appear on multiple devices.

Never senough such a thing. The name seems random. It doesn’t seem to be telling you anything.

Where are you getting the courses from?

The courses normally come from Garmin Connect.

I think I'm using the same SD card between the 2 devices -- maybe that's something I should look into.

The 1030+ doesn’t use SD cards. 

It’s not the result of moving the card. If the file system was corrupted, it’s very likely you’d get an error reading the file.

You don’t say whether things work properly otherwise.

Everything else works well. The problem happens on many routes which are normally transferred with Garmin Connect using my phone.

Whatever is going with your units isn’t not something people are reporting about. That is, it sounds like it is something going on with your particular unit. Maybe, you should consider resetting it.

It’s not likely its the file transfer.

The 1030+ doesn’t use SD cards. 

A good piece of detective work.

VanilllaBrys said:

I'm not sure how that alert got there, but it smells like a software bug to me.

Have you used the device recently in the rain without locking the touchscreen?

Even with the sensitivity set to the lowest level I find that any moisture on the screen quite often causes random touch events to be triggered leading to various unexpected behaviours.

 No one else has reported this (AFAIK). A “software bug” would likely be seen by more people.