I noticed that on the RAW search, if you click "More Criteria" there's an option for "Raw Repositories" but it contains no items. When you drill into, it does open a menu but since there are no items there's a single grey line.
The non-menu type items on this page have a more expected function: you pick them and they disappear from the list.
This issue is not limited to RAW. You can get this to repro with any menu item that has a second level by adding all the items in that item to the search.
I did not check older versions of NX3 or NX2 at this time.
Steps to repro (this is just the one the attached screen shows):
0) Do not need to login (unless your anonymous is messed up).
1) Click on + to expand Search
2) Click on Raw
3) Click on More Criteria
4) Hover over "Raw Repositories". BUG: Selector is blank.