Shot Status is not editable in certain shots

Hi - I have a number of shots, all of which have shot status’ but some of which are not editable. No idea what makes some shots unique from others. I have opened the permissions in the shot status field for everyone, but still these certain shots won’t allow their status’ to be changed. Any ideas why?

Actually I seem to have figured it out. I deleted some status items that I didn’t need and suddenly those status fields became active again. The only difference these shots had versus the other shots in the project is they were created before a site migration, but I can’t imagine that would have had an effect?