DeckLink Duo 2 and DirectShow fails

I'm migrating the video capture software for an industrial machine builder which will move to your DeckLink Duo 2 board.

The software moved from another video capture board using DirectShow and it always worked fine.

Starting from a clean W10 OS we have created a development system with DeckLink Duo 2 board.
Any try to get some frame in one of the 4 channels (DeckLink Duo (1..3)) failed.

I've downloaded your Blackmagic_DeckLink_SDK_12.9.zip to check with yours bin files.
Sample with your native API works (CapturePreview.exe).
Sample using DirectShow (DecklinkCapture.exe) return always a gray image, independently by settings.

Have you any suggestion about that ?
Best Regards
Silverio

After hours and hours of beating around the bush, I managed to get only 1 of the 42 graphic modes displayed for a Video Input of type "Decklink Video Capture (n)" to work.

Only the mode works:
width = 1920
height = 1080
format = '' (empty string)
bitRate = 1242915890

From Desktop Video Setup I see that the SDI is activated as "1080i59.94".

Not to fail I tried all 42 modes also with OBS studio and even there only that one
mode is available.

If you have more information on using DeckLink Duo 2 with DirectShow thank you in advance for any suggestions.