Hello Roberto nicolas
If I open the same file by double clicking on it, I can see that it can be opened in multiple sessions. This looks like a problem which I will check with the development team and get back to you.
However, I noticed that if I first open a blank session of Discovery SpaceClaim, then go to File - Open and open the file, and then if I try to open the same file through File - Open option, it does not open the file.
You are navigating away from the AIS Discovery experience