Hi David,
Thanks for your post, it seems like the Gerber viewer is having problems detecting or reading the outline layer properly. I suspect that the dot is from the drill layer (Eagle likes to overlay drill holes on milling slots).
The only way to really verify if the engineers will be able to see the milling is if we check the files for ourselves. The Gerber viewer is not the smartest and can trip over itself sometimes and Eagle updates keep messing with CAM files. Would you mind sharing the Gerber files here or via PM? Also, the design file and the CAM file used might help us determine if the configurations are correct.
Thank you very much,