I had problems getting both a new installation of Rapture Pro and Z3TA+2 to run in either Cakewalk or standalone in anything but demo mode. I downloaded a fresh copy of the Command Center from
https://www.cakewalk.com/Command-Center and installed it over the old one (possibly in administrator mode out of frustration), and all my problems went away.
Not sure if there is a new version of Command Center necessary for the new VST3 plugins or if it had to do with doing the installation in administrator mode. I had reverted to 8.1 from Windows 10 a couple weeks ago, and am not sure if I had updated Command Center since doing that, so that throws another variable into the mix.
Might be worth a try if all else is failing, I suppose!
Terry