There are some problems with uDynamic and nested content. When you select an item with the dropdown it shows the correct properties according to the rules, but it also changes this on all the other nested content items.

For example:

I select "media" in the dropdown and the correct properties are shown

I create another nested content item and select "content" in the dropdown, the right properties are shown.

I go back to the first nested content item, now the properties form the dropdown chooice "content" are shown

Great plugin by the way!