Please try the latest version 7.9.0. This version should fix your problem.
I am using version 8.2.0 and the same thing is happening to me. It seems that all large format pages are not working correctly. Try setting your page size to A1 and then plotting a test print. Only a letter size pdf gets generated. I work in large formats for cad and design work. It would really be great to be able to use the larger formats. Also, there are no landscape versions of the A series paper. Not sure about landscape on ARCH and ANSI series, but I will need these.