I've had and still have a few CCS100 units on my and my sons' bikes. I have found that for some unknown reason, one or other of then will not SET. I have also found that if the RES button is held in for a couple of minutes while cruising, it will eventually take over and working perfectly - until next time, which may be hours or days or weeks.
Another common fault it that the connectors get some surface corrosion, causing resistance which then prevents the unit from working or causes it to drop out soon after setting. I locate the few connectors/wires, unplug, spray with WD40 or similar then re-plug and unplug several times to restore a good connection.
Give those tips a try and report back.
The check valve in the vac tank can also fail causing issues. I've fitted a small inline c/valve on a couple.