Hmm… that’s strange… if you click the profile dropdown in your screenshot, then click “Browse All Profiles” do you see “Negative Lab v2.1” as an option? If you do, try cycling between “Adobe Color” and back to “Negative Lab v2.1” and see if that fixes it.
If you don’t see Negative Lab v2.1" listed as an option, you will need to try to add it again.
In Lightroom Classic (and Lightroom 6) the profiles “live” inside a designated folder location:
For mac, that location looks like this:
For windows, that location is something like:
C: \ Users \ [your username] \ AppData \ Roaming \ Adobe \ CameraRaw \ Camera Profiles
The Negative Lab Pro specific camera profiles live in TWO subfolders:
In your case, you will want to import all the profiles in the “Vuescan Profiles” folder - as this is what contains the the Silverfast and Vuescan specific profiles. Do NOT try to import just the profile you think you need, as the naming between the SF and Vuescan profiles is a bit confusing. Just import the whole folder.
In terms of Lightroom CC 2019/2020, once you import the camera profiles, they do not go into a typical standard folder, which is why you need to use their import dialog to manage profiles.
The whole thing is a bit annoying to say the least 
But hopefully that helps!
-Nate