Unable to add iPad Pro to AppleCare One Plan

Your screenshots help. The iPad Pro is showing under “This Device,” but it’s missing from both the eligible and “Not Eligible for Plan” lists.

I’d first make sure the iPad Pro is signed in to the same Apple Account that owns the AppleCare One plan. Apple specifically says a device missing from both lists may not be properly associated with that Apple Account. Add or remove a device from your AppleCare One plan - Apple Support (GW)

Add or remove a device from your AppleCare One plan - Apple Support

The fact that your other devices specifically say “purchased outside of eligible region,” while this iPad doesn’t appear there at all, makes this look like a different issue.

Yes, that’s a fair point. That rules out the Apple Account mismatch.

The next thing I’d check is where the iPad Pro was originally purchased. Apple lists the country or region of purchase as one of the factors that can affect AppleCare One eligibility.

If it was purchased in the U.S. and it still doesn’t appear in either the eligible or “Not Eligible” list, I’d use the Contact Apple Support link shown on that screen. At that point Apple would need to check the device’s eligibility record on their side.

I wouldn’t sign out of your Apple Account or erase the iPad for this. support.apple.com