If water is draining while the washer is trying to fill, check how the model drains and how the hose is installed. Siphoning can happen even when the pump is not driving it.
Is the water draining on its own, or is the pump running?
Note whether you hear pumping and whether the control panel shows a protection alert. The sound helps describe the episode, but it does not by itself confirm which component is acting. If continuous pumping is recognized, follow the diagnosis for a pump that will not stop.
On a gravity-drain machine, check that the drain selector has not been left open. Its installation is not comparable to that of an automatic machine designed to lift water with a pump.
Check the drain setup against its manual
The height of the discharge point, how far the hose is inserted, and the air inlet in connections where it is required all affect unwanted draining. Whirlpool documents this problem in its explanation of siphoning during filling; its measurements apply to the equipment described, not to all washing machines.
Do not seal with tape a connection that needs air intake, and do not improvise a raised position. Compare the setup with the guide to drain height, securing, and siphoning and the model documentation.
If the installation matches and the control keeps alternating between filling and draining, the level system and any activated protection should be checked. Do not keep repeating fill cycles indefinitely.
Distinguish this issue from water that comes back after the cycle ends: simultaneous inflow and outflow changes the diagnostic path.