Not intended at all! Probably a bug introduced by the latest patch.
Here’s a workaround:
- Go to Documents\My Games\Grim Dawn\save\user
- Go into your characters folder
- Create a new folder, name it something like ‘__other maps’
- Now move all ‘… .map’ folders of maps that you don’t want to play right now into the new folder
- ‘levels_world001.map’ is NydiamarMainCampaign; ‘Maps_nydiamar.map’ is obviously Nydiamar
- Do this procedure every time you want to switch campaigns
Hope that works for you!