mirrored body does not always follow the parent body

[luiyingchun]

The mirrored body ( on the right ) is created by create>mirror using the construction plane at the middle as the mirror plane.  As demonstrated in the video, the mirrored body does not always follow the changes made to the parent body.  Is this expected ?  There is no such problem in sketches.

[rajugupta8200]

Roll the history marker before the Mirror feature in Timeline, if you apply any feature on that body it will automatically updated on the mirror body.

If you are not roll the history marker the features are not updated. 

[davebYYPCU]

100% 

@luiyingchun just to confuse you, Copy Paste Component will likely do what you are wishing for.

Might help....