Problem accepting clock in from VCV Rack

I’m trying to sync VCV rack with the Model samples. Trying to get it to accept clock in so that I can use VCV as the master doesn’t seem to work. I’ve connected the CV-Midi module in VCV and I can see that a connection has been made (I can start and stop the Samples from VCV).

But when I try and change the clock from VCV, the tempo doesn’t change. I’m looking at the Tempo screen on the Samples and it sort of flickers to show “EXT”, so there’s some sort of connection, but the tempo doesn’t actually change.

I have the Midi settings on the Samples right, I think, so wondered if this was a limitation of the MS, or a bug, or maybe something I’m doing wrong in VCV?