Hello Pankaj,

While working with large models I have experienced a typical problem even for earlier versions. When I move spread sheet up or down some of the fields do not get updated. Sometimes, when I delete/modify support type the change is momentary. If you revisit the spread sheet you dont see the change you made just before. I think it is more related to processor speed than the software bug. For better working with large model I suggest to follow as below.

When you are working with the nodes in between the model (Not at the start/End) always generate a dummy element which connects the nodes on either sides of the node you intend to work with. e.g. you have model starting from node 100 to node 2000 with step of +10. You want to delete/modify at node between 500-600. First add dummy element from 400 to 700 (rigid 0 weight) before you modify/delete element at 500-600. This help to keep the co-ordinates intact and do not distort the model's overview. Once you are through with modifications delete the dummy element.
Hope this helps to resolve your problem. Good Luck.