Someone wrote in a reply somewhere that their clay baker leaked steam. The lid was slightly wobbly and didn’t create a tight seal.
Here’s something to try. I had an old ceramic slow cooker insert where the glass lid wobbled and was not a tight seal. I took a few strips of aluminium foil and lined the rim of the lid with it, all around. The lid no longer wobbled and it did seal in steam. I think I used heavy duty foil. The same could work on the lid of a clay baker and is certainly worth a try!