There appears to be a bug in the entry edit page when updating categories right from the category tab. If I add or edit a new category, the previously selected categories are unselected.
To reproduce:
1. Edit any entry, assign a category to it. Then click the Edit Categories link at the bottom of the list to edit or add a new category.
2. Add new category and press submit in the dialog or close the dialog without adding anything. (I think this is where the data gets lost)
3. Click Done at the bottom of the list.
4. The previously selected categories are now deselected.