Update: it’s working now!
It wasn’t an issue with the driver or the firmware. I was using a Thunderbolt PCIe enclosure (Sonnet Echo Express SE I) with the Yamaha Dante accelerator card and I guess that the accelerator card didn’t like being in it with Windows 11 because it worked perfectly fine with the Windows 10 PC that we are replacing. I also have a BlackMagic Decklink Mini Monitor 4K that was plugged directly into my motherboard’s PCIe slot, so I just swapped the two cards and now everything is working fine. The accelerator card is working perfectly plugged directly into my motherboard and the Decklink card is working perfectly in the Thunderbolt enclosure.