I'm on BIAB 2017 (456) and Alt 8 and Alt 9 (to mute melody / soloist) don't appear to be working any more???? Can mute from the mixer, but not using keyboard shortcuts. In fact Alt any of the tracks to mute is not working. Is this working as designed or is there a fault?

Windows 7 64 bit (I'm still working out whether to migrate to Windows 10 or not!!!)

Thanks
Peter