After data has been loaded into SDE 3.x, it's possible that the layer will not display correctly in the view of an SDE client such as ArcView or ArcMap. Specifically, the SDE 3 layer will not be centered in the client's view or may not even be seen at all.
This problem is due to inaccurate layer envelope coordinates that are generated on the initial load of the data. This can be verified by executing 'sdelayer -o describe_long'. The results of this command will show that the layer envelope coordinates are probably too large.
Another way to verify this problem is to select the entire extent of the view in the SDE client application. Verify that features are selected and then zoom to the extent of these selected features. If the layer is now visible, then the layer envelope coordinates are too large. The inaccurate coordinates cause the client's view to be zoomed out to such an extent that the layer is not visible.