If you only have problems with the Synthopedia presets, and it does'nt help to restart your computer, and reopen and login on your ASC before you open any VC applications, then you can try to download the Synthopedia installer from Arturias website and reinstall it using that.
If that does'nt help, then you can try to delete the db.db3 file in the preset folder. It's being rebuid, when you open applications. Make a backup of the old db.db3 file, just in case. If you only have issues with Synthispedia, then i doubt the db.db3 file is corrupt, but one never knows.
Be certain that Synthopedia is activated.