Shell unregisters itself after Explorer restart, Register button does nothing afterwards

[Lezoxxu]

Hi,

I'm on Windows 11 with Nilesoft Shell 1.9.18.

Here is my exact issue:

1. I install Nilesoft Shell → it works perfectly on first launch
2. I restart Explorer (via Task Manager) → Shell stops working,
   native Windows context menu shows instead
3. I open shell.exe as administrator → click Register →
   it asks to restart Explorer → I confirm → but nothing changes,
   native menu still showing
4. Clicking "Restart Explorer" from the Nilesoft window
   also has no effect

So Shell works only once after a fresh install, then it's impossible
to re-register it without reinstalling completely.

What I tried:

• Running shell.exe as administrator
• Checking Windows Defender history → no blocks found
• Multiple fresh reinstalls

Is there a way to re-register Shell without reinstalling every time?
Any idea what causes Shell to unregister after Explorer restarts?