May be, but i don't consider it a bug actually. here the thing is we are trying to show some very close values on line chart and obviously the space issue will occur. I recommend you to use A bar chart or a combo chart and check values on data points also go to presentation and select plot inside the chart.
This isn't a bug, you have data points that are very close together. You may be looking for a feature that exists in Excel, for example, that allows you to set if the data is above or below the point.
This doesn't exist in QlikView, but you can fudge it a bit by using the DUAL syntax to put an invisible symbol that can show the value just below the line.