I have set up categories and sub categories and was hoping with front end editing I could let the authors select their own category what publishing articles. However, some of the categories are grey and aren't selectable.

From a lot of messing around, it seems to be something to do with levels.

My category "tree" looks something like:

Cat 1
- Cat 1 Sub 1
- Cat 1 Sub 2
- Cat 1 Sub 3
Cat 2
- Cat 2 Sub 1
Cat 3
Cat 4

All of Category 1 and subcategories are ok and selectable. After that, when it goes back to a "parent category", the category becomes un-selectable in the front end.

In the back end I have no issues. Just a front end problem.

Any ideas???

Please check that you haven't limited the categories to be edited from the settings you have for your K2 User Group.

Ahhh, seriously! Thank you Yiota! That's it, solved.

My first thought was that is was a permission issue but was only looking in "parameters" and at user permissions.