# Why do some of the characters in my included PDF file show up transparent?

I'm trying to include a PDF file in my LaTeX document (I'm using pdflatex), which looks as follows:

\documentclass{article}
\usepackage{graphicx}
\begin{document}
\includegraphics[page=1]{fdt1}
\end{document}


The PDF file looks fine if I view it individually, but when I look at the resulting new PDF file, some of the characters appear in outline only, which is to say, e.g., all the M's are outlined and all the A's are normal (filled in).

The PDF file in question was also produced by pdflatex, by combining two other PDF files that have been converted from SVG using rsvg. For what it's worth, all the PDF files are OK according to qpdf and JHOVE.

Here's what pdffonts has to say about the fdt1.pdf file:

\$ pdffonts fdt1.pdf
name                                 type              emb sub uni object ID
------------------------------------ ----------------- --- --- --- ---------
DMXJUV+NimbusSanL-Bold               Type 1            yes yes no       5  0
NBAIUF+NimbusSanL-Regu               Type 1            yes yes no      10  0
NBAIUF+NimbusSanL-Regu               Type 1            yes yes yes     16  0
DMXJUV+NimbusSanL-Bold               Type 1            yes yes yes     20  0
NBAIUF+NimbusSanL-Regu               Type 1            yes yes yes     26  0
DMXJUV+NimbusSanL-Bold               Type 1            yes yes yes     29  0


Does anyone have an idea of what might be going on here and how to fix it?

Edited to add: This seems to be some sort of weird font issue. It turns out that the problem goes away if I change the font for the title line in the image. (That would be in the source for the fdt1.pdf file that is being included.) If the title is in Helvetica (which the diagrams also use), the problem shows up, but if the title is in Avant Garde it goes away.