Decklink DUO 2 not recognizing video

Simple signal flow:
A Canon W10, little camcorder, with mini HDMI out, adapted to HDMI, going into a HDMI to SDI converter
of the inexpensive chinese type, into a Marshall 3g-SDI monitor.
The monitor displays the picture and says its 1080P 60hz.
I go either direct or through the monitor to an input of the DUO 2.
Desktop Video says it is seeing 1080P 30hz.
OBS acquires black (no picture) from the input.
Can anyone explain what is going wrong?
I assume that the monitor is correct that the camcorder is putting out 60hz, being that
the monitor displays the picture. What would trip up the DUO 2 to thinking it was 30hz and
not pass the video?
The DUO 2 is receiving and properly processing a 720p signal on another input.
I have a few months experience with OBS and the DUO 2, I've been getting good predictable
performance until introducing this camcorder.

Sounds like it could be a 3G SDI Level issue. When sending 1080p60 video over SDI, there are two different formats 3G SDI Level A and Level B and not all hardware is universally compatible with both.

Another issue with some of the inexpensive generic-brand HDMI to SDI converters, is that they don't always use SMPTE-compatible SDI chipsets (SMPTE sets the standards for the broadcast and professional video markets). Instead they sometimes use lower cost SDI components designed for the security camera industry. This can sometimes cause issues with hardware from Blackmagic and other manufacturers that does comply with SMPTE standards.

My suggestion would be to use one of the Blackmagic HDMI to SDI Micro Converters instead, as this will let you set the 3G SDI Level to use on output and is more likely to work with other Blackmagic hardware.

Many thanks That was an education. Yes, I'll avoid these security camera level devices in the future.
That level A and B business must cause a lot of confusion.

Update:
Black Magic Micro Converter HDMI to SDI works correctly.

Changed the title of post...
Thanks for the pointer!

Hi. I'm using three cameras with Blackmagic converters and having this issue too. One of the cameras is showing correctly his video, but the others are showing black screen. The audio is being correctly recognized but screen is black. This is happening in the Blackmagic software and OBS, but in Vmix no camera is showing nothing at all...