After upgrading to 1.5. we experienced a very strange issue with the categories. We define the categories in our ERP and upload them to Magento. That worked perfect in1.4. Now in 1.5. when we try to allocate a product to a category we can see only the main category without any subcategories. When I open the category overview directly, I can see all categories and are even displayed in the shop.
The interesting point is, when we manually add a new subcategory the all subcategories will be displayed. But as soon I delete the manually added category, all subcategories are hidden. Please see attached file with some screenshots.