This could be related to 2 issues;
Open file explorer and in the URL type desktop. If the icons appear in file explorer, issue is related to users resolution when working from home is different to when working from to office.
To change this minimise the RDP and on the users local machine right click select display settings.
Scroll down to scale and change it to 100% on all monitors.
This change will automatically happen on the RDP too. Icons will then appear on the users desktop.
If the above does not work the issue is related to users having icons set to hidden, to revert this change:
Right click on the desktop > view > show desktop icons
Icons will then automatically appear on desktop once this is ticked.