I just got an hd60x and obs studio 29.0.2 on my mac mini with 10.15 (catalina); I get audio, and the video showed the elgato logo at the beginning but it is not showing content, though the monitor hooked up to the hdmi output is showing it. Now the preview window is just black (after replugging cables and restarting obs)
logfile: https://obsproject.com/logs/oqQSvhp308ZDaTW5
logfile: https://obsproject.com/logs/oqQSvhp308ZDaTW5