Steps to reproduce:

1. Open VE
2. Click on Insert --> Graph
3. In general settings choose Line Graph as type of graph.
4. Go to raw mode
5. Enter the following values of x and y in an attempt to plot the line graph with equation y=-x;

x: 0
y: 0

x: 1
y:-1

x: 2
y:-2

x: 3
y:-3

Observation
The plot does not take the expected shape of a y=-x line graph but just shows a horizontal line.

Video given below: