I've never had issues with iOS - discovery is near immediate every time. The only time I've had issues is when sharing with random people that have it set to contacts only and we haven't shared a contact, or if someone turned wifi off manually.
On the Mac though, it is a different story. Just yesterday my wife was trying to send me a PDF and I had to send it to my phone from her Mac, then dump it into iCloud Drive. I rebooted my Mac and then it worked again - but these are stock 2018/2019 Apple laptops, they shouldn't have these issues.
On the Mac though, it is a different story. Just yesterday my wife was trying to send me a PDF and I had to send it to my phone from her Mac, then dump it into iCloud Drive. I rebooted my Mac and then it worked again - but these are stock 2018/2019 Apple laptops, they shouldn't have these issues.