i cannot see airplay icon

I am running High Sierra on an old MacBook Pro. I recently rest it and reloaded High Sierra and now I have lost the airplay icon from the menu bar. I have set the firewall to allow incoming connections and ticked show mirroring options in display settings. I can mirror youtube video to the Apple TV by clicking the icon on the youtube screen, but cannot mirror my computer screen, or anything else without the menu icon. How do I get it back?

Up to recently I was able to send Foxtel Go from my iPad Pro to my Apple TV Using the airplay button, it has now vanished, been on line to check if others have the same problem yes

did all the checks recommended, like turning airplay off then on the Apple TV, it has the latest version of software and iPad Pro is up to date on its software.

Tried the airplay 2 icon the pull down menu but only the sound worked no video ?

Help please

Do you mean activated it in Finder>Preferences>Sidebar?

Any luck yet?

Sys Prefs>Displays>AirPlay Displays checked ON?