As I have no answer about this issue I downloaded 2 sets of .vit and .val files on this forum.
https://forum.seamly.io/t/intersect-point-axis-error/2539/2 https://forum.seamly.io/t/fixed-points-that-grow-shift-with-sizes/2618
and tested them. Yes the pattern file can be opened and linked to the measurement file, so they work.
But I will also have to explain to my students that Seamy2D is a curious software as you do not have to “close the pattern” before quitting the application otherwise you get an incomprehensible error message… or maybe there is another reason but the support hasn’t got a clue of what’s wrong.