Well this gets a little more interesting. The tabs showed up on the desktop hours later but never showed up on the laptop. Looks like I won't be able to use this feature because of its instability, i.e., it doesn't work.

Hi spcl.stuff,

• Ensure notifications are allowed in both the devices.
• If yes, then disconnect both devices.
• Sign back in to Firefox on both devices and hopefully the send tabs will be working again.

I got similar problem. I send a tab from Android to Windows and it didn't arrive. I even clicked Sync now but nothing. I tried to relogin on both devices.