They should appear if there is a proper install.
I am running LabVIEW 2019 for Linux Desktop installed on CentOS 7.6 and my VI Server page under Tools>Options is fully populated.
What OS are you using? That will probably help NI Support provide answers.
LV 2020 on Ubuntu 20
I'm wandering if the sections are loaded from a file that is in the LabVIEW folder
After some additional digging : It was working on LV 2020 and the issue appeared after installing the SP1 patch.
I think there is an issue between my xfce ubuntu distro and the patch, there was an error when applying the core package.
Tried with kde and gnome, got the same issue.
As currently ubuntu is not supported it's not too surprising.