I've been using the gerber viewer on PCBWay to check over the PCB i'm working on and have encountered a strange issue. Hopefully somebody can shed some light on it as i'm new to PCB design. I have a feeling this may be difficult to explain.
Note: The gerber viewer flips the board horizontally, the EAGLE view does not.
Everything seemed to be in order. This is the bottom of the board. I noticed one of the vias was stopping the ground pour connecting down the side of the board. So i went back to the eagle file and nudged it so that the ground pour was continuous.

Here you can see the via just to the right of R17, below the top right pot, which is breaking the pour.

Here it is nudged to the left to allow continuity.

Now when i export the gerber files again and upload them into the PCBWay gerber view all the traces disappear from the bottom of the board:

What kind of fresh nonsense is this?