I have Cubase 10 Pro. I downloaded the demo for Studio One 4.
When Studio One ran for the first time and scanned for plugins I received the following warnings for two plugins (Addictive Keys & Addictive Drums 2);
Wrong binary location. This binary is not the same as the one updated by the XLN Online Installer. Please check your path settings by clicking the 'Advanced button' in the XLN Online Installer and make sure it matches the plugin path setup in your host
You are now running from: c:\Program Files\Steinberg\Vstplugins\
The XLN Online Installer thinks it should be in: C:\Program Files\Vstplugins\
I haven't followed the instructions in the warning yet because I am afraid of messing things up for Cubase 10, which has never had a problem with these plugins.
I also note I have many other plugins that were not picked up. In fact only very few of them were.