I have this issue when connecting my 2021 iPad Pro to my brand new M1 Max Mac Book Pro running Monterey 12.1 using the Thunderbolt/USB-C ports. The iPad runs iPad OS 15.2. It rarely shows up in finder or system report thunderbolt or USB ports. Sometimes it does show up. Sometimes that's stable, sometimes not. Same behavior with my wife's 2021 iPad Pro, and with different Thunderbolt cables. As a control, connecting my iPhone 13 Pro via lightning-to thunderbolt cable works fine. Thunderbolt external drive also works fine except daisychaining does not work. External Thunderbolt hub connects fine. So in this case, there is a specific bug connecting the iPads to my M1 Max Mac Book Pro. Connecting via thunderbolt to an older Intel MacBook Pro running Big Sur worked, as did connecting via thunderbolt 3 to thunderbolt 2 adaptor to an even older Mac Book Pro.
RatioDelectat1
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