I recently updated to MacOS Mojave and encountered a very strange problem in DPP4. I cannot throw images into the trash anymore. I did give the DPP4 application permission to control my computer in the privacy and security settings. I updated DPP to version 4.9.20, but it did not make a difference. All the other features seem to work. Has anybody any idea how to solve this peculiar problem in the software?
After assisting a friend to upgrade his Apple Mac to Mojave 10.14.XX he encountered the same problem of not being able to reject files to the recycle bin.
Without having to add DPP4 to the full disk access as you suggested, but by simply checking the box under, System Preferences / privacy / Automation has corrected the problem.
Kudos to you for finding the answer and for taking the time to share it with the Canon community.
I encountered a similar problem. It seems that DPP4 doesn'tnecessarily prompt the user for the appropriate user permission in Mojave. Do this manually, access System Preferences -> Security & Privacy -> Privacy Tab -> Automation to ensure that the Finder box is checked beneath DPP4 (see screenshot below).