Cylinder and Boss will resize appropriately when the Thread tool is applied to the face. Otherwise you get a "Cylindrical face diameter is in conflict with thread definition." While it will still place the symbolic thread, the diameter will not change. Old tools for old tools. Cylinder & Boss work well with Thread (add Pocket to the list as well).
I have edited the thd_english.dat file to add new threads in the past, found in your install directory, UGII folder.
If using a sketch extruded or revolved the diameter can be linked to the thread feature expressions.
Create a sketch
create extrude/revolve feature
Create Thread feature, accept diameter mismatch warning
Edit sketch, edit dimension controlling the diameter that is threaded, link to thread expression
Not as automatic as Boss feature with Thread feature but it does work.
+1 Kudo simply for the praise of Inventor over NX.
I'm telling you I have the worst trouble with NX. I tell people it's like a fully functional car. Yeah it's got a brake pedal. But you have to reach into the backseat floorboard, dig around, and press it with your hand.
Using NX is like that.
On topic: Same problem. Only the important bits on the dialog box are greyed out. I get to pick the face and name it "George" but still nothing. Can't pick from table either.