Airdrop not working; Bluetooth connected. Did all other troubleshooting too
Handoff and Airdrop would possible not works in anytime in my experience when on iOS 12, it works better when comes to iOS 13 but could still fails.

And this morning I found a why while my MacBook and iPhone could find each other but my iPad, reason is the IP address of iPad is 192.168.8.xxx while MacBook and iPhone are within 192.168.9.xxx.