Other Win 10 PC not found in "Share with nearby devices"?

[lectrocrew]

I'm running Windows 10 (version 1809 on both machines - 1 laptop / 1 desktop). When I try to share from my desktop PC to my laptop, my laptop is found (see 1st image 'MikeHP2000') and the file transfers correctly.

But when I try to share from my laptop to my desktop PC, my desktop PC is not found. (2nd image).

To the best of my ability I have all the file sharing settings exactly the same for both machines.
As far as I can see all of the Windows Defender firewall settings are the same on both machines.
I'm not very knowledgeable about networking stuff so any help is appreciated.

[lectrocrew]

Update: The desktop PC is now being found by the laptop but no window pops up on the desktop PC in order to allow me to accept the file transfer like it does on my laptop. Where do I enable this incoming file notification popup? I my "Settings > Notifications and Actions page, all notifications are enabled.