No Handoff icon in dock I'm missing handoff icon in dock. I remember that when I had open safari/messenger on my iPhone, I could easily click on the icon that showed on left side of dock.

It's not there anymore. What could be the issue?
Handoff is working correctly, I can copy text from mac->iPhone, and iPhone -> mac, I can open website on iPhone from Mac.

The only issue is that I am missing the icon.
Video: https://youtu.be/--MMBRgPvFs
this is what I have observed. your tab in iOS was in private  mode and macOS was in normal. so it was easily transferred to iOS but got opened in private mode which in turn could not be opened in Mac. 

Do tell me if I am wrong.