VideoInputFormatChanged not working with 10.4 drivers?

We use both the older Decklink SDI Duo cards and the newer Decklink Studio 4K cards in our application.

With the latest 10.4 drivers we are no longer getting the detected SDI input format reported (VideoInputFormatChanged callback) for either card.

The BMDDeckLinkSupportsInputFormatDetection flag reports true and we pass bmdVideoInputEnableFormatDetection to EnableVideoInput.

Using the older 10.2.2 drivers for the SDI Duo card reports the detected format correctly. Obviously we need to migrate to the newer drivers for the 4K cards (they fix other issues on these cards).

Our application is currently built against an older SDK (10.1) for compatibility with older deployments. I have though tried the 10.4 SDK's though with no success. Has something changed in the way we need to use the SDK to get the detected SDI input format via the callback?

(Linux test1 3.11.0-26-generic #45~precise1-Ubuntu SMP Tue Jul 15 04:02:35 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux)

Quick note to say this turned out to be an (incorrect) assumption in our application code which is no longer valid with the newer drivers. After tweaking our code, the format change detection works as expected.