I think, overall, the current lack of ability to use your DVC reservation number will not have a major impact on the vast majority of DVC Members. It will, of course, potentially be very bad for those trying to book hard to get reservations, most notably the popular charatacer meals. But for the average run of the mill reservations, those few hours most likely won't matter.
Considering that the call-in dining line can now see our DVC reservations numbers and link into it, there is no reason for it NOT to work, other than poorly tested and executed programming...typical Disney IT. They seem to always be rushed projects that are released full of bugs and missing functions that are fixed later. Why would we expect this ADR booking program to be different?
That is because you are within the 90 day mark, when everyone, even offsite guests, can book ADR. The DVC glitch comes into play if you are trying to book exactly at 90 days out, and are wanting to use the 90+10 feature. This would be for those really hard to get character meals, or during the "free dining take no prisoners melee."