OT midi to Volca#1 to sync Volca#2 don't work

Hallo.
I have issue to connect two Volcas to my OTmkii.
I send Midi clk. out to Volca drum, but i need to sync it with my Volca bass.
I was expecting syncing volcas thru cable would be easy, but somehow it don’t work… Volca bass don’t resieve sync IN from volca drum, ( its tempo knob is 0).
Volca drum is in midi1-6 mode and recieves midi from OT.
When i unplug midi cable from volca drum, syncing via both Volcas works well.
Anny ideas?