Compute Stick into ATEM Switcher

Hello.
We have 12 old "ATEM 1 M/E Production Studio 4K" units in our squash and tennis courts. They have SDI camera inputs, please one Intel Compute Stick as a HDMI input to overlay a web page.
A couple of years ago, one of the ATEMs stopped working, so we got a "ATEM Television Studio HD" unit instead of it.
No problem. All inputs work great.
Last week, another one of the ATEMs stopped working, so we got a "ATEM 1 M/E Constellation HD" unit to replace it.
The SDI inputs show up fine on the Constellation unit. But the Compute Stick does not. Since it's HDMI, we're running it through a HDMI to SDI Blackmagic 4K converter. The converted signal shows up all purple and green. Very discolored.
When I connect this exact same compute stick to the other ATEMs, it shows up fine. So it's not broken.
Any ideas if there settings or something else I need to change to get the colors to appear correctly?
Thanks.
We have 12 old "ATEM 1 M/E Production Studio 4K" units in our squash and tennis courts. They have SDI camera inputs, please one Intel Compute Stick as a HDMI input to overlay a web page.
A couple of years ago, one of the ATEMs stopped working, so we got a "ATEM Television Studio HD" unit instead of it.
No problem. All inputs work great.
Last week, another one of the ATEMs stopped working, so we got a "ATEM 1 M/E Constellation HD" unit to replace it.
The SDI inputs show up fine on the Constellation unit. But the Compute Stick does not. Since it's HDMI, we're running it through a HDMI to SDI Blackmagic 4K converter. The converted signal shows up all purple and green. Very discolored.
When I connect this exact same compute stick to the other ATEMs, it shows up fine. So it's not broken.
Any ideas if there settings or something else I need to change to get the colors to appear correctly?
Thanks.