Missing files on SD and CF Express B cards

I did a series of headshots yesterday for a client. I photographed everyone that was there, imported the files onto my hard drive and dropboxed them all the raw images for them to edit.

I get an email today saying there is a person missing. The guy says he went to the photostation around the time of another person (midway in the shoot). I looked through all my images, he is not there.

All my RAW files are sequential, there is no break at all in the numbering. I was not shooting tethered, I had no camera malfunctions during the shoot. As part of my workflow, I take one image and check the LCD for a quick light reference. While I can't guarantee I did this for the missing person, I typically have been doing this over years.

I am shooting with an R5, and have RAW images sent to my SD and to the CF ExpressB card. Both cards are identical in content, his images are nowhere. I was taking 4-6 photos person, and this would mean that each one of those images, and only those images, are missing.

Anyone have any similar experience or issues? Or any input at all?

All I can do is, being no fault of my own, is simply head to the guy's workplace and reshoot the images. No worries, a few hours of time for travel and setup, but whatever. Its still a huge mystery for me.