“To add a caption, it seems you must do so straight after uploading the picture/image before saving/embedding. Once you’ve added the caption, it can be edited freely afterward.”
I don’t think so, at least in my case. This happened after updating WP. Had no problems with it in the past.
I have the same problem. For two years the caption on the image works. All of a sudden I guess after I updated wordpress, I noticed the captions were outside the image! It looks bad. Anyone suggest a solution? Check out our blog:
http://www.mbmclassictravel.com/blog/
Notice that in the old post up to June 13, all captions were ok inside the image frame, but later its bad.