UltraStudio Recorder 3G not negotiating w/ Canon 5D Mark III

I can't get any Canon 5D Mark III to negotiate HD modes with the UltraStudio Recorder 3G. I've tried with 3 separate cameras and 3 HDMI cables, including Canon's own. Media Express reports a signal of

Code: Select all

525i59.94 NTSC, 8-bit YUV 4:2:2

(480i effectively) and goes red if any other format is selected.

The camera's Mirroring feature never activates. This happens regardless of whether or not HDMI time codes are enabled, and happens regardless of HDMI frame rate setting between auto, 24p and 60i.

I've heard reports of the Canon 5D Mark III working on other BlackMagic capture devices after firmware updates. Could my Recorder be missing such an update?

Tested on all Camera firmwares between 1.2.3 and 1.3.5, Blackmagic Desktop Video 12.3 and 12.4. Running macOS Monterey 12.6.1. I've confirmed I can capture 1080p from other sources using this UltraStudio Recorder 3g.

If someone at BlackMagic needs a Canon 5D Mark III to test on, please let me know and I will lend one.