Reaper-x64 here too … and W10-x64, i7, 32Ram. On my system I can add as as many PS tracks as I want … no problem changing presets … and no problem adding more PS tracks or deleting PS tracks … UNTIL … I have one PS track left. With 1 PS track … if I delete that track and try to add another PS track … Reaper leaves the building.
KenB