Michael N

See if this will work for you:

I encountered the same problem. I loaded a song that contained SI Bass and the SI Strings and got a message saying that the SI instruments were missing or not installed properly. All the folders for the SI were present in my computer but Cakewalk by Bandlab did not scan the VSTs properly. I really don't know if uninstalling and reinstalling Cakewalk by Bandlab would have solved the problem but I definitely couldn't reinstall the SI Suite because the addon install of the Studio Instruments Stuite was greyed out for me but I solved the problem by launching the old Cakewalk Command Center (luckily I did not uninstall my old Sonar Platinum) and proceeded to reinstall the Studio Instruments Suite. I suppose that, if you no longer have the Command Center you could download the Suite by logging into your old Cakewalk account and possibly reinstall your old version of Sonar if needed.