Mark,
I've seen something like this once and it turned out to be a corrupted asset.
Can you get the object?
It appears to be a broken track-object like a track-mark, or something.
If you get it, you can then see what it is and then verify that it's corrupt or not in Content Manager. If it's not built-in, you can download it again, or reinstall it from CDP.
You might want to run a DBR afterwards too just in case.