When controlling the VHT UL/100CLX with the CFX4 and this cable, the following applies;

CTL1 off CTL2 off	Clean
CTL1 on CTL2 off	Lead
CTL1 off CTL2 on	Rhythm
CTL3 on/off	EQ
CTL4 on/off	Boost

CTL1 - CTL4 must perform LATCH type switching, not momentary, so;

If you're using MIDI Program Change messages to control the CFX4, follow the "Edit Control Configuration" section in the CFX4 user manual and configure the CTL functions listed above for LATCH type switching.

If you're using MIDI Control Change messages to control the CFX4, ensure your MIDI footcontroller is setup to transmit the MIDI Control Change messages for LATCH type switching as listed in the CFX4 user manual.