I have High Sierra on my Imac, Itunes sees my Ipad but Finder does not recognize it.

Finder in High Sierra is not designed to recognize an iPhone or iPad. Only Finder on Macs running macOS Catalina or later will recognize iPhones an iPads. Before that iTunes is used for the same functionality that Finder is now used for.

Also see Use iTunes to sync your iPhone, iPad, or iPod with your computer - Apple Support including the following from that support article:

If you're using macOS Mojave or earlier or a Windows PC, use iTunes to sync content to your devices. 

It's working properly. The Finder isn't supposed to show it in Mojave or earlier, and there isn't any disk access to it in newer OSes.

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