V is sand ... too much power and you slip ... start the throttle just before you release brakes ... If you let the consist start rolling down the grade backwards, you are done for Cab mode is most difficult.
I had similar issue on the moJave to Barstow Sessions, darn AI would not be able to get moving after stopping uphill, I ended up using sanders, throttle up some and then releasing the brakes slowly until it got solid forward motion. probably the wrong way, but then again, so is using the e-brake to start a manual uphill in Cisco fo rthe first time.