I would try toggling “Use Audio Units” and “Use VST Plug-in System Folders” in the Preferences off and then on again. For whatever reason, sometimes simply hitting “Rescan” doesn’t do the trick.

Just to tell that this solution (for the vst part) needs to be applied with a new install for Ableton Live 10 Suite 64 bits (Windows 10 Pro)

Simple rescan does not work, neither restart of Live.

Best

Didier