I think I found a bug introduced with the new version (1.0.30) concerning the “Implicit Rests” colours (great addition IMHO).
When exporting, even with the “View options” ticked off (which prints things like voice colours, if I understand that right), the implicit rest colours (greys and voice colours) are exported in the PDFs.
Setting the colour to “Mono” is a workaround, but I think that the rest colours should not print with the “View Options” off.