Machinedrum Not Passing MIDI Clock When Slaved

I have a Machinedrum UWII that is sequencing an Access Virus C that is also using its clock dependent fx and arppegiator. When the Machinedrum is the master the two machines stay in sync perfectly.

However, when Ableton is slaving the Machinedrum, the Virus falls out of sync with everything (even though it indicates it’s receiving some sort of clock signal). I can change the tempo in Ableton while playing and the Machinedrum shifts fine, but the Virus is completely oblivious of this.

If I attach the Virus to the MIDI Thru of the Machinedrum though, the Virus is in sync fine again. How do I fix this? I’ve checked all sync settings in all machines. Thanks.