Greetings
No IRS realign in flight,
alignement realign requires the platform to be stable. no acceleration, no movement, sometimes the movement created by loading container is enough to screw up the align process, on a modern Airliner.
Now looking at your plotting
there is a shift (bias) between ploted and aircraft position, WGS84 coordinates aside, cross-check your initial position values, specificaly the last digits (sometimes gates coordinates are wrong
) verify with a hand held GPS.
That's all I can think of
