Certainly not the first person with this so some sort of hardware conflict or bad hardware is out there.
https://community.pix4d.com/t/4125-Failed-to-write-Exif
https://community.pix4d.com/t/3581-Error-Failed-to-write-Exif-data
My rig has processed a failed project without issue so it isn’t a global issue but something that needs fixed. In the meantime, I do processing as a service if you need to get some projects done before this gets resolved.