1. Find a popup menu. The accounts list in the "from" field when composing an email is one I use for this test. Insure VO is on.
2. Press space or down arrow to open the menu, then press the down arrow once, or the first letter of any item in the menu.
3. Now repeat the action. Focus moves to the new item in the menu, but VO repeats the value of the item it was on before. I have to up or down arrow, then do the reverse, to bring focus back to the current item for VO to actually speak it. This appears to be consistent. At least, I can reliably reproduce it.