Where to place VST instruments in Cubase Elements 11

Hi, I have just upgraded to Elements 11 and have downloaded BBC Symphony Orchestra Discovery. It shows up in VST Plug in Manager as enabled, but does not appear in the Add Track/Instrument dialogue box. I also downloaded the VSCO-2-CE instrument library for use with Sforzando, but Sforzando cannot access it.
Can anyone suggest possible reasons/solutions?
I have been in contact with both support services, but so far without any success.

I am running Windows 10 64bit on a PC with a dedicated hard drive for musicproduction

Did you updated your plug-in list inside the plug-in manager?
Otherwise new plug-ins will not be available.

Hi Steffan,
Yes, and checking the Plug in manager shows it is there, and it is enabled. But when I try to add a track with it as the instrument. it does NOT show in the add track/instrument deialogue box.

Is there a custom list activated? You have to update this as well

I can’t see a custom list anywhere. What would it comp[rise and where would I need to look for it?

Can you provide a screen shot of your plug-in manager window?
You can add custom plug-in lists there…