I know this is an old question that I'm replying to, but I found this post while searching for an answer to a different Citrix problem and I would like to offer some information in case anybody is still having the problem.

Our Problem:
In our environment we noticed when upgrading from Receiver 4.9 CU5 to Citrix Workspace App 1912 CU1 that Citrix App shortcuts were not showing up on the desktop for users. We have the "Show apps on desktop" setting configured via group policy and we have the Mandatory keyword in a lot of our Citrix apps. This all worked fine with Receiver, but with Workspace App, whether it was an upgrade to Workspace App on an existing endpoint or a new installation on a new endpoint, the user's Citrix Apps would not enumerate on the desktop unless the user opened the app pick list or ran a WSA reset.

Solution That Worked for Us:
Add the following Reg strings:
x64 machines - HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Citrix\Dazzle
RefreshMs = 3600000
InitialRefreshMinMs = 1
InitialRefreshMaxMs = 1

x86 machines - HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\Dazzle
RefreshMs = 3600000
InitialRefreshMinMs = 1
InitialRefreshMaxMs = 1

Enabling Prelaunch on Endpoints also seemed to help with this issue. See the below Citrix Article for more info:

https://support.citrix.com/article/CTX239186

Passthrough authentication is delayed on Workspace App for Windows 18.8.0.19031
Article | AuthenticationConfiguration | 2 found this helpful | Created: 29 Oct 2018 | Modified: 29 Oct 2018
Symptoms or Error
Pass-through authentication is delayed on Workspace App for Windows 18.8.0.19031 Once user logs on to desktop, Workspace App does not log in automatically. User has to right click on Workspace App icon in system tray and click on logon. Application shortcuts are to be placed on desktop - This is enforced by policy. As Workspace App does not log on, apps are also not enumerated on the desktop. If user closes Workspace App and reopens from Start menu, logon is instant.

Solution

Make sure the following registry keys are present:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Citrix\Dazzle
RefreshMs = 3600000
InitialRefreshMinMs = 1
InitialRefreshMaxMs = 1

Use Receiver GPO to enable Prelaunch if it is required

Problem Cause
Prelaunch behavior has been re-designed in newer Receiver/Workspace App

You might benefit from this
https://www.carlstalhood.com/receiver-for-windows/#registryvalues