Just updated to 13.0.51 in order to make my new CS12 be compatible with Cubase. I can no longer connect my scarlet 4i4’s outputs 3/4 to the phones in the control room. As see in the video. As soon as I connect and play audio it drops out. Same behavior if I disconnect main outputs 1 and 2 and only connect 3 and 4.
I use a Mac Studio M2 MAX with the 96gb of ram.
Looks like a driver issue, as here, the Control Room works perfectly when allocating hardware to headphones, as long as there is a hardware stereo output available.
So, just in case… There are two different tints displayed in the Outputs column of the Focusrite Control window. Isn’t this due to the fact that Monitor Outputs 1-2 are activated, the other ones being disabled ? If the case, maybe, when attempting to connect your Outputs 3-4, the driver, not finding the relevent activated outputs, throw this message as a kind of error management.
Can’t say much more, as I don’t have a Focusrite hardware unit to test this. 
The two different tints in focusrite control are to show which parameters are in focus. In this case I was on monitors. This has no effect on if the outputs are “on/off”.
The screenshot was to show the focusrite is at 48khz like Cubase.
i’ll post as solved as this is not Cubase related and is 100% related to the Scarlett 4i4
