I have been using Aure for over 4 years now so know my way around.
My new installation of Axure RP 8 does not seem to set the output page size correctly. The reason I know that this is Axure rather than a printer driver is that it is affecting both printing and writing to a PDF file. I have to physically set the page size each time a try and print.
For the PDF, the Adobe PDF Page Size setting is blank. It appears to be clearing this default setting as elsewhere the default displayed is A4.
When I access the printer preferences pop-up it sets the paper size to 56 x 79mm. If I change to A4 and print then everything is great but if I exit the print preferences and return later then it reverts back to the 56 x 79mm.
I was having the same problems with Axure 8 Beta so abandoned using it as I didn't have the time to figure out what the problem was. Now I have upgraded 7 to 8, I don't have that luxury so need to find a solution. I should have maybe stuck with 7.0 but thought it was just a Beta bug that would now be sorted.
If anyone else has had this issue or knows of a solution I would be grateful for any help. I have googled around but not found anything.