Lines not visible in line chart export

[Lines not visible in line chart export]

We are using the exporting code and accompanying SharpVectors dlls from v3.7. It doesn't appear to be browser specific, as it's occurring in both IE11 and Chrome. The charts themselves are built with v3.3 due to various reasons, but when the same SVG data is rendered using an online tool like JSFiddle it displays exactly as expected, so the SVG data is valid and contains all the necessary information to render the lines correctly.

[Lines not visible in line chart export]

When we export line charts using the .net exporting wrapper the lines between points are not visible. This is shown in the top part of the attached image.

 

We are using SVG data which we have already verified as containing the relevant information using other SVG rendering methods. Is there any way to fix this issue?