Why do I get the message that the AirDrop Failed due to not enough space when I have over 50GB of free space?

I see this question has been asked a number of times with no real answer. I have an 256Gb iPhone 12 Pro. The device currently has 142.2GB used so the device has at least 50Gb of free space as can been seen from the screen shot below:

I am trying to transfer an .mp4 file of 2.11 GB and I'm getting this message. I should say I've already transferred 3 other mp4 files of various sizes the largest was 2.76 GB.

Why can I not transfer this file?

It's clear that the failed transfer attempts are cached somewhere on the device, as I've forgotten I'm transferring and walked away which has caused it to fail. But a device restart has cleared that and I've been able to continue. APPLE please can you answer this

Thanks

Simon