ATEM Mini: unexplained latency on Macbook Air

Trying to decide whether or not to return my new ATEM Mini.
HDMI Out latency 100-150ms
USB-C to OBS on Windows 10 PC 200ms
USB-C to OBS (or Facetime) on Macbook Air (OSX Catalina) 1000ms+

I can run the same camera through a video capture card (August VGB500) and get 200ms to the PC and 200ms to the Macbook.

It's driving me mad. All I want to know is why? We know the signal out from the Mini isn't delayed (because it isn't delayed to the PC) so it's not internal processing delay within the ATEM. We know the Macbook can handle input from a video capture card without added latency. What could possibly be causing the Macbook to create an additional 800ms+ delay on the signal from the Mini vs a video capture card?

I think I'm having the same problem, but not on all services.

ATEM mini (new), s/w version 8.2.3
ATEM software control panel, s/w version 8.4
Mac Air OS Catalina 10.15.6

Camera is Lumix G series (new)
new cabling

Camera feed to HDMI monitor out shows minor latency.

Feed to Zoom conference call and the latency is a full second. Cisco Webex is very small. Google Hangouts is in the middle.

I wouldn't be surprised if it was related to the issue many of us are having:
viewtopic.php?f=4&t=116634

Whether it is or not, please make sure you contact Blackmagic support so that they are aware of how widespread the issues with the ATEM Mini are.

I'm seeing exactly the same issue on a MacBook air (Catalina), MacBook Pro (Mojave) and Mac Pro (Catalina): my ATEM minis work very well on Windows laptops, with minimal latency. They're delightful. But when I plug them into a Mac the video latency is a second or more, so audio leads video by a similar amount. They're unusable.

I've filed a support request.

With macbook air you have to be careful because the computing power is not high. To solve the problem and bring the latency to an acceptable level you have to lower the video quality in the setting of the ATEM Mini to 29.97 fps or less