Random Font Deactivation

I have a machine at work, and a machine at home.

Both are iMacs. Both are running MacOS Mojave. Both are using Font Explorer 6.

My work machine, which is actually newer has a very strange font issue. Activated fonts will randomly be deactivated. I can have FontExplorer X Open, Adobe Illustrator open and suddenly the fonts are just not activated and a default font replaces in the OPEN Illustrator file.

Font Explorer shows the fonts activated. In order for them to be recognized by the system, I need to turn off the fonts (that show that they are active) and then turn them back on again.

My machine at home is running pretty much an identical set up. But I do not have those font problems.

I've run all the font cleaning/cache cleaning set up on Font Explorer X several times. I even turned off Font Explorer and explored other options, but they seem to have the same issue. Fonts just randomly turning off.

A possibility might be a DropBox issue, but the Font Explorer X folder which houses all of those fonts is not under a DropBox directory.

I've spent many many hours trying to resolved this, with no success. I finally had to add my essential (non system) fonts to the Library > Fonts directory so they don't turn off in the middle of a project.

Does anyone out there have any ideas why this would be an issue? Again my home computer with almost identical setup does not seem to have this problem.