As you can see on this block diagram, NUC11PAxxx does not have a native HDMI port. It is using a DP->HDMI protocol converter (PCON) chip. It is more than likely the source of your audio passthrough issues. So this is not a gen11 issue but an issue specific to that NUC model. There is nothing to fix from LE/Kodi side.
I thought the lspcon issues were solved long ago in 5.x kernels
Also it used to work on my 5thgen with LE 9/10
I am, guessing this is a new issue.
Does anyone know if the hdmi2.1 on the N100/200 are native? Asus doesn't have diagram, and I don't trust the one from asrock.