Limited to 16 inputs in OSX Yosemite with Aggregate Device?

Being driven mad here… I use an aggregate audio device in OSX 10.10 - it’s a 32in/14out device according to the OSX AudioMidi Setup applet.

In Cubase Pro 8 Device Setup, it is only showing as 16in/8out. So I can’t choose the other I/O in VST connections.

This setup was working OK in Cubase 7 - and I have tried everything I can think of, changing the device, recreating the aggregate under a different name etc.

Jiggling the order of the devices in the aggregate lets me choose different I/O - but never more than 16in/8out are available or shown in the Device setup window.

Grateful for any ideas - Am I being dumb here? Just can’t see what might be wrong!

im on pc which wont do aggregate other than specific brands eg. maudio that use a common driver as cubase only sees one but are all your device sample rates set the same assuming each has its own control panel?

So… investigated further, and not sure this is Cubase’s fault. It’s happening in Wavelab and Cubase 7.5 too.

Seems the issue occurs in the situation where different sample rates (and drift control) are used within the aggregate device. This is new behaviour, since this configuration was working fine on this machine before - but it is not clear to me what has changed.

Frustrating - now I will need to run everything at 96kHz…ouch!