Solved
I can't make the file to be 3.0 readable.
I know. It's ridiculous that version 3.1 can't share data with version 3.0, but that's the way it is.
You have a vector within a vector (note the double braces on each side). Nested arrays like that are allowed in Mathcad, but you can't plot them against each other. Delete one set of braces.

