Lost video files during import

Scenario: friend comes to me with his iPhone 11 Pro Max, running iOS 14.7.1 and needs help importing photos and videos to his Mac Mini (Late 2014) running Yosemite 10.10.5. We select import and delete files after import. At the end it gave us a list of 391 video files that were incompatible that couldn't be imported (all .Mov files). We hit ok because it was the only option. Now his phone is missing those video files. They don't appear under videos. And as far as I can tell it wasn't imported into his Mac Mini.

How is it that an incompatible file that couldn't be imported was deleted as though it were imported? Are these videos lost? Where can we look for them?

And as you can imagine this guy does NOT use iCloud. I feel really bad for him because I was helping him.