Hi bibikit,
The support page How to use AirDrop on your iPhone or iPad offers the following suggestions:
- "Make sure that the person you're sending to is nearby and within Bluetooth and Wi-Fi range.
- Check that you and the person you're sending to have Wi-Fi and Bluetooth turned on. If either of you have Personal Hotspot on, turn it off.
- Check if the person you're sending to has their AirDrop set to receive from Contacts Only. If they do, and you're in their Contacts, they need to have your Apple ID's email address or mobile number in your contact card for AirDrop to work.
- If you're not in their Contacts, have them set their AirDrop receiving setting to Everyone in order to receive the file."
As you have this set for Contacts Only, confirm that each of you have the Apple ID address stored in the contact information. Edit contacts on iPhone shows how:
"In the Contacts app , assign a photo to a contact, add a pronunciation, change a label, add a birthday, and more to your contacts.
- Tap a contact, then tap Edit.
- Enter or update their contact information.
- When you’re finished, tap Done."
Regards.