I’ve just done a clean installation of my OS, and have installed Cubase 8.5 with the latest patch, and have installed my plugins. In the Plug-in Manager, I have designated the folder which contains both Amplitube VST and VST3 plugins, but Cubase only loads the VST plugin, and not the VST3 plugin.
Am I trying to load it correctly? Anyone know why it it doing this?
I found a way to solve the problem of Cubase not loading Amplitube 4 VST3, and that is to put the Amplitube VST3 file in the Program Files\Common Files\VST3 folder - which, by the way, isn’t where I keep any of my VST plugins. I have multiple boot OSes on a single machine, and I access Cubase from multiple boots, and so I have a secondary drive that contains all my plugins. I set Cubase up so that it loads the folder on that drive that contains all my plugins, and Cubase was able to discover all of my VST2 plugins from there just fine, but couldn’t find the VST3 plugin unless it was in that specific Program Files\Common Files\VST3 folder. WHY???
Then why even have plugins that ask which folder they should be installed to, when they only work from one possible folder? And why is there no documentation anywhere detailing this? I did many internet searches, searched Steinberg’s articles about VST3, and nothing mentioned this very critical detail that VST3 ONLY WORKS FROM A SINGLE FOLDER. I made a hopeful guess to try moving the VST3 file to the default folder to see if that would make it work.
What a shitty, inconvenient, and non thought-out file format, to be restricted in this manner. I’ll be sure to avoid VST3 in the future.
Just an FYI about using Amplitube 4 VST3…
This VST3 has a bug with Cubase. Not sure if the bug is with all versions of Cubase but definitely 8.5 and 9. The bug has to do with the plugin bypass button being missing on the plugin pop up screen. Read all about it on the IK forum. This is not a Cubase issue. IK needs to fix it.
I loaded the AT4 VST 2.4 (or whatever it is) because of this issue.
Regards. 
VST3 plugins should really be installed into the correct folder without asking or any option to change it.
I’m surprised there would be an option to change vst3 location in the IK installer.
EDIT: I just updated Lurssen Mastering Console and can confirm IK do give the option to change install directory for VST3!
If you want to install to a shared drive for dual boot o/s I think you would have to do something like create a symbolic link to them from each o/s common folder though this may be more trouble than it’s worth and just installing two copies may be easier.