I have a figure made in the print composer, but when I "Export as pdf, both the legend and our company logo disappear.
Any idea why?
I have not had this problem before. Using QGIS 2.18.10
To translate my comment as an answer:
You can export the layout as image instead of PDF, then in any image processing software you can open the image file and save it as PDF.
I am not sure if this is a bug or not in QGIS 2.18.10, but at least I did not face the same problem in the QGIS 2.14.19 LTR version.