I had a similar problem (where objects with a mask were missing or mangled during pdf export) and found a workaround. I found this open bug while googling the issue, so I figured I would share it in case other people have the issue before it is fixed.
I exported just the object by right clicking it and exporting it to a file, then opened that file and replaced the original object with the version from the file. I don't think this is ideal, but it worked in my situation.
I had a similar problem (where objects with a mask were missing or mangled during pdf export) and found a workaround. I found this open bug while googling the issue, so I figured I would share it in case other people have the issue before it is fixed.
I exported just the object by right clicking it and exporting it to a file, then opened that file and replaced the original object with the version from the file. I don't think this is ideal, but it worked in my situation.
version: Inkscape 0.48+devel r11533 (Jul 11 2012)