Normal, you can’t find it on any Elektron. Nor Control All (NRPN ?). Feature request !
(MD Control All machine can be midi controlled, so is OT Crossfader)
(There is a kind of workaround for midi FILL for Octatack with One Shot but it is not easy to set up ! 
)
Midi command for FILL Mode? - #4 by sezare56
Ah I forgot midi CC for velocity.
Can be used as midi FILL. Not easy to set up too.
Syntakt standalone music - #1360 by sezare56