Input via webform - System does not allow to feed value for one of the period

Summary:

I was trying to feed % values to a member via webform and I was able to edit and submit the data for all months except January. When the period was selected as January, system is showing as non editable field. All members in the intersections are selected with lowest members as you can see in below screenshot. What could be the possible reason? January does not contain child member. Also please find below dimension properties of Jan and Feb member with no difference

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