Report graphics do not render

Basically, my issue is I'm applying my learning to a real life scenario whereby I have configured a BI environment but some report graphics will not render and I really need urgent assistance with this issue. I'm sure it is some kind of configuration problem perhaps IE.

Some background - I'm using a 3-server topology (DW, SSRS, SSIS) all running SQL Server 2014 Enterprise. The Report Server is Windows 2012 R2 running IE11. My local machine runs IE9 (and this is the network default). The strange thing is when I DebugLocal the report renders on my machine perfectly with the DataBars and SparkLines showing fine. However, when I browse to the Report server (native mode) and click on the report from there, then the report graphics do not render but instead all I see is a tiny icon instead of each individual graphic.

Can someone guide me through what areas I need to check configuration-wise?

Obviously as I'm able to view the report correctly locally then I'm assuming this isn't some kind of 2014 bug.