Hello kirstyjaym,
If you're unable to send files through AirDrop, here's some things you can check:
Make sure there's no VPN or security software installed on the devices. You can go to Settings > General > VPN & Device Management, to see if anything is installed.
Make sure you don't currently have any restrictions set up for AirDrop. Go to Settings > Screen Time, and see if that's currently enabled. If it is, proceed to Content & Privacy Restrictions, and see if that is enabled. If it is, go to Allowed Apps, and make sure the toggle switch for AirDrop is currently turned on.
You can also try doing a network reset to see if that fixes in. Settings > General > Transfer or Reset > Reset > Reset Network Settings.
How to use AirDrop on your iPhone or iPad
If your AirDrop file transfers still just sit on "waiting", you'll want to contact Apple to report that issue: Get Support
Cheers!