Boeing's Bulletin:
BACKGROUND INFORMATION
737 service history indicates that flight crews may not recognize or correctly interpret the autoflight system automatic transition to the Control Wheel Steering mode.
Automatic transition to CWS may occur while engaging the autopilot or when it is already engaged. Examples are attempting to engage the autopilot while not following the flight director commands, or force override through the control column or wheel with the autopilot engaged. The reversion to CWS mode may not always be easily recognized by the pilot
You can still use CWS P in the altered FCC software by disengaging the current pitch mode (e.g. press VNAV in climb).
FMC U11 should be released in first half of this year.