Preview Monitor Garbled Image - [solved]

I'm having a strange issue, one that is ongoing.

Briefly, my signal chain is as follows:

ATEM Constellation HD M/E 2 multiview ---SDI --> BMD SDI-to-Optical ---Fiber--> BMD Optical-to-HDMI ---HDMI--> Extron XTP T USW 103 4K ---Ethernet--> XTP SR HD 4K ---HDMI--> TV

When the above signal chain is active, the image from the ATEM looks like the attached image. When the Extron portion is removed and the TV is hooked directly to the Optical-to-HDMI, it looks fine.

Spent almost two hours with Extron tech support trouble shooting everything, and everything on their end checks out -- EDID, cables, firmware, all of it. AND, when an HDMI source other than the Constellation is the source, the entire signal chain works fine.

We tried dozens of resolutions and settings on the Extron input, changed the multiview output to different settings too. Even wrote a custom EDID profile.

SO, something about the Blackmagic Optical-to-HDMI output is not being read correctly. Does anyone have any ideas?

EDIT: changed subject line to solved.

A followup on the solution I achieved, mainly because I dislike finding a post from the past that has no answer.

Disclaimer: While I have a solution that works, I do not fully understand why it works. If anyone wants to fill in details that'd be great.

I posted this same issue on the AVSForum, where a respondent noted that as the ATEM output is YCbCr 4:2:2, and many devices that have an overlay function--like the Extron--convert to RGB, the issue being experienced as outlined in my original post was probably due to a color space swap happening.

I had a Decimator on hand that does color space conversions, so I updated my signal chain as follows:
ATEM Constellation HD M/E 2 multiview ---SDI --> BMD SDI-to-Optical ---Fiber--> BMD Optical-to-HDMI ---HDMI--> Decimator MD-HX ---HDMI--> Extron XTP T USW 103 4K

Using this setting on the Decimator, the image was perfect.

This setting fixed things

deci_output.jpg (31.33 KiB) Viewed 286 times

What I don't understand is why does this fix it? It seems like the conversion is changing the ATEM signal TO YCbCr. That seems backwards to me, unless I'm reading it wrong. Or is there a missing flag on the HDMI output of the Optical-to-HDMI Teranex that the Decimator is simply conforming correctly?

To finish the story, getting accurate color output from the Extron needed these settings:
(apologies for a picture of a screen)

Extron_output_settings.jpg (21.88 KiB) Viewed 286 times

To wit, I'm now seeing what I would expect:
(again, apologies for a picture of a screen)

fixed_output_settings.jpg (52.14 KiB) Viewed 286 times