failed to save item. Save to iCloud Drive Instead

I am trying to send videos from my iMac to my iPhone with no success, it's not saving to my camera roll. I used to be able to do this but I don't know why out of a sudden this started to happen. I tried the below but I'm still having the same problem.

1- I updated my softwares on both devices

2- I tried converting the mp4 to mov

3- I deleted files from my gallery

4- I tried sending the video via Whatsapp then save it from there

Please help me.

Thank you