iPhone has activation lock but is not listed in iCloud devices.

If it's locked to a different Apple ID, you need to log into that one, or contact the person who can, or if you're the iPhone's original owner, supply Apple with its purchase receipt.

If it's locked to your Apple ID and an attempt to turn off Find My iPhone for it didn't take, supply Apple with its original purchase receipt.

(181603)

There have been reports here of people who turn off Find My iPhone for a device but it doesn't get properly processed. When this happens, the Apple ID used to lock it can no longer activate it, and the only solution is to have Apple bypass the lock.

(181605)

See Turn off Activation Lock https://support.apple.com/en-us/HT201441. All possibilities related to iPhones, iPads, and iPods are covered here except the case of inheritance.

If you are the original owner: If you have iOS 11 or later and your account is protected with two-factor authentication, use get help with a forgotten passcode or disabled device to recover your passcode. Otherwise, use forgot your Apple ID or your Apple ID password to recover the needed credential(s). If you can’t recover the needed credential(s), contact Apple Support and present your original purchase receipt for your device from an authorized Apple seller with the device’s serial number on it. You’ll need a photo ID too.If you can do neither, then the device is useless to you.

If you acquired your device second hand, you usually will need to obtain the needed password from the person that last set it up. If you can’t obtain it, in the rare case your device came activation locked from an authorized Apple seller, then contact Apple Support and present your original purchase receipt for your device with the device’s serial number on it. You’ll need a photo ID too.* If you can do neither, then the device is useless to you.

In both cases, you can use the suggested support options below. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.

Get a call from Apple support to help solve your problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific andregion-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.

*Rarely, an iDevice is purchased activation locked from an authorized Apple seller.

Thanks Neil. I'll look into what you say.