Yes, the Ajax now works as it should.You found that fast! (thanks). However, the other problem I mentioned still prevails That is when a new checkbox appears using this technique and it's checked and then the profile is saved, the fact that the selection is checked is not saved. I looked in the database afterwards and I don't see any selection stored in the codemulticheckbox field. If I then go back and edit the profile again and check the box that appeared during the previous edit and update again, then the selection gets saved to the database. I am wondering if there is something else needed in the PHP code that returns the options list or if perhaps there's another bug.
This is turning out to be a pretty good test for this field type!