I've confirmed this is happening in Version 1.6 and the latest 1.X dev branch.
Steps to recreate....
- Create a new website with the default recipe.
- Add any field type to any menu item type. Html Menu Item for example.
- Add an Html Menu Item to a navigation menu, and fill in the field.
- Immediately after saving, click edit on your menu item and you will see the issue.
This problem seems to go away if you re-enter the field data after creating. It just doesn't take on the initial item creation. The field data does appear in the ContentItemRecord table, but it's not in the ContentItemVersionRecord table which seems to be related
to the issue.