HDMI to SDI micro converter problem

We have a small school studio which is using the ATEM 1 M/E Production Studio 4K. This switcher only has 1 HDMI input. We need more. Want to run one from a PC (to play videos) and one from a Mac to create green screen backgrounds.
When we plug in the PC into the HDMI input, we can see the PC on the Multiview screen
When we plug the Mac in the HDMI input, we can see the Mac on the Multiview screen.
We thought we could purchase the BM Micro Converter to HDMI to SDI and simply run either the Mac or the PC HDMI through the box and output an SDI into an SDI input on the switcher. But we do not get any image on the Multiview when we do this. We updated the software to the converter and tested all our cables. But still nothing.. What are we missing?
We are using 1080i 59.94 and tried other settings as well, but nothing.
Tried 1080p, 59.94, 29.97 and no luck

The converters support higher/other resolutions than what the switcher is running at - so you need to manually force the output resolution of your Mac / PC to be the same as the switcher.

When you're connected directly to the switcher, EDID does this for you (*well, mostly) , by conveying that "this display (i.e. switcher input) can only take resolution so-and-so, at frequency so-and-so."

Especially for macs, the frequency is often overlooked (and defaults to 60Hz), even if the main resolution is set correctly.

I would advice you to look at this tread:
Frequently Asked Questions - Atem Mixer >Point 1.02

But to be short. The send resolution of the Laptop need to match the resolution and framerate of the Atem. Also the micro converter (When using 1080P on the Converter be sure Level A / B is correct in the Micro converter configured.. (See miniconverter software))

Better way for connecting laptops is almost everytime using the BMD UpDownCross V2 or Decimator MD-HX This will ensure everytime you get a correct image.. Even if the laptop is screwing up again..