Thank you for uncovering the cause of the problem, and for explaining what needed to be done to correct it.
After I went through the steps in your reply, Reflect this evening has retained 16 full images in my J drive.
You wrote "...I'm not sure how the one in your Documents folder disappeared from Reflect or how you ended up storing a definition file in Reflect's Program Files folder..."
I cannot explain why 2 files named "My Backup.xml" were found on my PC.
I first read about Macrium Reflect back in 2014, in Leo Notenboom's "Ask Leo!" newsletter.
When I saw how well Reflect worked I purchased both Reflect and Leo's book "Saved! / Backing Up With Macrium Reflect".
On 5/2/2014, following the instructions in his book, I saved my first "My Backup.xml" file in my Documents folder.
For some reason Reflect apparently saved another file with the same name in the other path; "C:\Program Files\Macrium\Reflect\My Backup.xml".
Because Reflect has been working with (calling?
) the file that is in my Documents folder, I imported that file into Reflect and edited it to retain 16 full backups.
This evening, when I saw 16 full backups in my J drive, I removed the other file from the Backup Definition Files tab in Reflect.
Thanks again for your help,