Diagnosis
The internal real-time clock circuit is losing its memory retention. This is caused by a failing capacitor on the main control board that provides temporary backup power.
How to Fix It
There is no user-serviceable fix for the capacitor. The workaround is to use the microwave's 'Kitchen Timer' function for timing needs. The clock error does not affect cooking functions.
If That Didn't Work
If the time loss is accompanied by other malfunctions (e.g., settings not saved), the entire control board is failing and requires replacement.
Heads Up
A complete power outage will always reset the clock to 0:00. The issue is defined as losing time while the unit remains plugged in and powered.