RDCMan v3.21 failing to redirect drives

After updating to RDCMan v3.21 my RDP sessions no longer access my local drives.

Steps to reproduce:

1. Clear all settings, including Global settings (close all RDG files and rename %USERPROFILE%\AppData\Local\Microsoft\Remote Desktop Connection Manager\RDCMan.settings to "RDCMan.settings.old")
2. Open RDCMan
3. Create a new RDG file (e.g. File / New / "test.rdg")
4. In the new RDG file, "Add [a new] server ..."
   • On the "Logon Credentials" tab, enter your server's logon details
   • On the "Local Resources" tab, be sure C:\ drive is selected for redirection
   • Go to every tab and remove "Inherit from parent"
5. Connect to the server
6. In the RDP session, open File Explorer 
   • Observe that your C: drive is connected ("C on [client-machine-name]" is present)
7. Logoff the server
8. Save the RDG file ("File / Save All")
9. Close RDCMan
10. Re-open RDCMan - this should show the new RDG file with the server
11. Re-connect to the configured server
    • If you are prompted to trust the server's certificate, say "Connect Anyway"
12. In the RDP session, open File Explorer 
    • OBSERVE THAT YOUR C: DRIVE IS NOT AVAILABLE

No matter how I specify Local Resources (explicitly in the server properties, inherited from parent folder or global settings, etc.) after re-starting RDCMan, the drive is never made available. I have reproduced this consistently several times. MSTSC (Remote Desktop Connection) works every time (my drives are available in the RDP session) so this is not a group policy issue.