Clear plastic appears white-ish when rendered?

Hello everyone,

I have been working on creating a pen in SolidWorks and have rendered the final assembly numerous times.

The appearance of the tubing and tip of the pen are set to 'Translucent Plastic'.

The first few times I rendered the pen, the plastic tubing and tip came out as expected (clear and shiny - as shown below).

However, whenever I render the pen now, the tubing and tip appear white-ish (shown below), even though I have not changed any bloom/colour settings of the plastic. Can anyone explain why this is happening?

I have also tried rendering in clear glass, which works fine but does not have the same desired effect as plastic (shown below).