Chart Displaying Data with Unwanted Offset

I'm not sure why there is a 50 point offset from 12900 to 12950 on the X Axis when "LC @Now Profit" and "LC @Expiry Profit" (columns I and J) are added to the Long Call chart.

There is nothing I can think of in the inputs in the formula that should cause this.

The lower blue straight line on the chart changes angle up at 12950 but it should do this at 12900 like the blue line above it? Any ideas?

Cheers!

Had to add image 3. Not sure why image 2 doesn't appear in full?