Could you list all audio output devices, that Kodi shows and also all available output devices, which are listed in Batocera Sound Settings?
You can upload your pictures on a website like abload.de for example (or any other imagehosting website)
Here some photos of one of my systems with Nvidia GTX 750:
As you can see, there are a lot of different Audio Output Devices i can choose from.
It is a bit hard to see on the second photo, but the correct Audio Output Device of my GTX 750 is the light-blue highlighted one on the second photo ("HDA NVidia, SAM SyncMaster on HDMI #2").
In Batocera i then had to choose "HDMI2 NVIDIA [HDA NVIDIA]" to get sound via HDMI.