I fully agree with you Beastieboy,
For the moment I disable dugi to prevent the errors when saving UI changes.
Go to ui setup and edit the properties for objective window and make it as small as possible and drag it as low on the screen to give Dugi some room to breath then save it and reenable Dugi and I find it to be an acceptible workaround until a solution can be found or maybe info on how to disable the objective frame in Blizzard default addons. I hope this tip works for you.