Several HOURS! That's something. Could you try the latest internal build at:
https://cdn.stardock.us/support/uploads/Fences5_5.8.4.5-j138-Setup.exe
to share more?
This copy has extended logging ability which will help collect data and send a report.
(1) Uninstall, using the option to "keep your settings". Reboot.
(2) Install the new version. Go to the About page and select "Enable advanced logging". Reboot.
(3) Collect data! Reproduce the situation a few times, taking backup snapshots before/after where you can, and then ultimately using that Create error report package link to create a package. That'll give us ability to take a closer look. It's also possible that the new build resolves your issue.
Thanks for your help figuring this out together!