Midi and Thunderbolt

I have an old Auria EQ 276 and use an adapter to connect the USB-c to a DP connector on the monitor. The image is great but the audio has been hit or miss. Sometimes the speakers work and sometimes they don't. Before we get into cables, I have tried all kinds of combinations and replacement cables.

I have found an odd solution. If I open the MIDI set up program and jigger the format, it starts to work. I can set it to anything but moving the setting selected to something else will make it start working.

Why does this work? Is it going to be the same when I get a new monitor/ speaker?