Not sure if this covered, but an extensive search didn't show anything.
I've written a custom post type and all is working. I put data in and it saves ok. All good.
Except I need to add an additional field to the type. I do this, all is ok except that all custom post data is lost when I go to a previous post.
Is this a bug or by design? Can I get around this as I may need to make changes down the line and don't want to lose all of my data.
Any ideas or advice?