Probably a bug: I have assigned the 2nd Soft Key to Multitrack Playback / STOP. If I press that button a 2nd time after the transport is stopped, the recorder locks up and I have to eject the memory card to get it unstuck.
We’ve not been able to reproduce this – could you please contact us directly through support.allen-heath.com with details on the CQ (model, firmware, serial number) and SD card (manufacturer, model) so we can look into this further.