B747-400 Captain reported the low-speed amber band and stall red band move above the flaps maneuvering speed during departure and flap retraction.

Narrative

UNRELIABLE LOW SPEED AMBER AND RED BAND DURING FLIGHT.During departure out of ZZZ the Low Speed Amber band and Stall Red Band moved above the Flaps Maneuvering Speed during departure and flap retraction. This presented a dangerous scenario presenting false maneuver margin information and a potential Stick Shaker Activation. The Airspeed had to be monitored and controlled in such a way as to avoid this.Similarly during the approach and landing into ZZZZ the same scenario presented itself except this time the auto-throttle low speed protection feature activated and in addition to that the bank angle had to be limited to 5 degrees as the airplane came within 2 knots of a Stick Shaker activation.The incident was written up and logged in the Aircraft Maintenance Log and the airplane grounded pending maintenance action on this problem. It is to be noted that the exact same problem also occurred out of both ZZZZ1 and ZZZ1 a few days earlier enroute to ZZZZ2; where a log book write up was also made and the airplane grounded pending maintenance action.A right side AOA was replaced and tested ok. Upon arrival to ZZZ there were small airspeed maneuver band error indications noted on the arrival but nothing showing on the Advisory EICAS or recorded in system history. The airplane was then re-dispatched to ZZZZ3 where we again experienced significant anomalies in the Airspeed Maneuver Band; resulting in direct pilot action being taken to avoid an inadvertent Stick Shaker.It has become clear at this point that this on going dangerous issue and needs to be resolved immediately before the airplane flies again.