Show tabs not working with 2011 iMac

[glenthompson]

I have 4 devices signed into iCloud, a 2011 iMac (High Sierra), 2015 MacBook Air (Cataline), iPad Pro, and iPhone XR. Onall the devices except the iMac I can hit the show tabs button and see the tabs open on the other devices except the iMac. Likewise the iMac doesn't show any of the tabs open on the other devices. According to the Apple documentation, this is supposed to work on MacOS version of Sierra or higher. I can't upgrade the iMac as it's maxed out at High Sierra.

Any ideas of why this isn't working?

 

[appltech]

If you read apple's article on the subject between the lines, you might catch that "Tabs works between devices running iOS 13 or iPadOS or later and macOS Mojave 10.14.4 or later, or between devices running iOS 12 or earlier and macOS Mojave 10.14.3 or earlier".
I read this as "you can sync tabs either between older OSs, or between newer OSs", meaning you cannot sync tabs between macOS 10.13, and macOS 10.14+ or iOS 13+.
Please correct me if I'm wrong.

 

[glenthompson]

If you read apple's article on the subject between the lines, you might catch that "Tabs works between devices running iOS 13 or iPadOS or later and macOS Mojave 10.14.4 or later, or between devices running iOS 12 or earlier and macOS Mojave 10.14.3 or earlier".
I read this as "you can sync tabs either between older OSs, or between newer OSs", meaning you cannot sync tabs between macOS 10.13, and macOS 10.14+ or iOS 13+.
Please correct me if I'm wrong.

Good catch, I missed that subtlety. It's a strange demarkation. Would like to upgrade the iMac but the GPU in it prevents doing the hack to upgrade.