Updating missions on the workshop can sometimes fail.
If updating a mission, more specifically updating a mission with the [DLC Required] tag targeting Making History on the Workshop page, the upload will fail, and it will instead create a new workshop item.
This causes the initial mission to lose lock with the initial workshop item, preventing the user from updating their mission without editing the steamPublishedFileID value in persistent.mission to that of the original workshop item.
#3 Updated by JPLRepo about 1 year ago
There is a workaround described here on the forum: