I had a different issue with the workshop, decided to make a preset to save the list of mods I have.
Because of a different bug, I have to delete the mod folders from my \ArmaReforger\addons folder.
After deleting the mods, I tried to reload my preset so I could re-download the mods, but the preset won't load unless I have the mods downloaded.
I expect the preset to allow me to download the mods if I don't have them installed