In player setup, you can add a solo player or a section player, but you can’t change a solo player to a section etc.
This is a problem where, for example a project is incorrectly specified or imported. E.g. the sample projects (take a look at the strings for the Pigmalion sample for example). NotePerformer chooses different samples depending on this setting, so for that example, all strings are played as solo instruments.
in order to correct this, one would need to add a section player, copy and paste then delete original (can’t cut and paste or it gets it all wrong), then delete the instrument. Changing solo to section shouldn’t be that hard, section to solo I could imagine trouble with existing divisi settings, but they could be split into separate players or something. In the 3 projects I’ve opened I’ve had this problem, so I think it will be common.