My Passport Ultra is not backing up some files

I’ve been using My Passport Ultra for about a month and everything seemed to be getting backed up.  However, today I did some work on my computer which created new files.  Once I plugged the My Passport in, it did it’s backup.  However, I spot checked a few files and some items didn’t back up to the folders.  Where did they go, or why did these files not back up.  The (2) files that I noticed were PDF files created from Quicken.

Hello there, welcome to the community.

Have you checked if this files are protected somehow? Also, where is the location of the file?