Which model receiver? I am not doubting you, just want to get information, see, my D10s all pass the CC to the TV untouched, then my TV controls it, additionally, at least with my D10s, there aren't even any CC controls in the receivers menus.
I do, however, see different CC methods, including the kind you talk about, it seems to me, that the bouncing around could be controlled by the broadcaster as well as the user-end equipment (STB/TV, etc).
Interesting, I don't suppose there are any kind of menus for CC in the HR20s menus?, perhaps it has a way to turn it off (and maybe if set to off, it would pass the CC to the TVs control?), if not, that could be a real issue for those who need CC.
I have used the closed caption on both an HR20 and HR10-250 and from what I've seen, it depends on the show as to how the captioning is displayed. Sometimes it will stay at the bottom and scroll, sometimes it will bounce around as discussed, etc. The same thing happens on both receivers.