External HDMI display issue (Ventura and Sonoma)

Hey all, I don't know if this affects everyone but we are updating some 2019 Mac Pros at work and the HDMI output now seems to have lost the ability to actually change resolutions. The options are there, but changing them doesn't actually seem to change the output resolution and the resolution seems fixed on the maximum supported resolution of the connected device. Has anyone else experienced this? For what it's worth, I first noticed this when a machine was upgraded from Monterrey 12.6.1 to Sonoma 14.7.1, but we have since updated another system to Ventura 13.7.2 and the same behavior was witnessed there. Our setup is probably a bit unique, we have the HDMI output connected to an AJA HA5 which can support resolutions up to 1080P, but we need to run the output at 720P because one of the end devices doesn't support 1080P. In Monterrey and before, choosing 720p in the system prefs worked fine, but now it doesn't. I can see in the AJA configuration software that the detected resolution stays at 1080p60 unless I manually force the HA5 EDID to a lower resolution.