Unable to sort in grouped ListGrid

Using smartgwt-3 I'm facing a client-side problem while sorting an already grouped grid.

Having an extended ListGrid

Able to sort the grid when it is not grouped by any field, but when its grouped by some field its not getting sorted using the grid's sort() method after applying the SortNormalizers.

Sample code:
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Step 1) ListGrid is dynamically grouped on some filed1

Step 2) Now trying to sort the grid on same field.
grid.setSortNormalizer(new SortNormalizer().....)

Then sorting is not happening

Moreover I am getting ListGridRecord with missing attributes whatever is set.

Could you please reply to this ASAP.


Thanks in advance