When I go to edit to add more seasons, I get a lock view and no way to add seasons.

To quote the FAQ,

The "Ended" and "Cancelled" TV Show Status now automatically disabled the "Add New Season" button. New seasons can't be created when a TV entry is set to Ended or Cancelled. [...] For ended/cancelled series with a missing season, you are allowed to temporarily change the TV Show Status back to "Returning Series". Just don't forget to set it back to Ended/Cancelled when you are done adding the missing content.

What you should do in these cases is set the status to Returning Series to unlock the ability to add new season, add all the missing seasons, and then go back to fix the status. If you cannot do that because the content was locked by a mod, file a content issue report explaining the situation.

Thank you for the details Banana!

Banana,

This was working for missing series but it looks like I found a series that I'm unable to update to "Returning Series" so I can't add the 3rd season. Has this functionality changed? I've seen it work but I'm not sure why this record is different?

Totally Outrageous Behavior https://www.themoviedb.org/tv/19975-totally-outrageous-behavior

The status was locked. Should be working now.