@BeccaC I feel your frustration!!!
However, as @adeshgupta1996 pointed out just a few posts above yours, there is a work around. You can just use the FILE>PRINT>PRINT PDF instead of EXPORT to PDF. If you don’t have acrobat then you may need to install a different PDF writer, there are some mentioned in the thread above.
I’ve given up on there being a fix for this. Im one of the original posters and have been looking for a solution for nearly 2 years now (first had this issue in november 2017!) - which is ridiculous!
As @chaz_plan says, the PDF quality using PRINT PDF is not as good as EXPORT but after hours poured into this thread looking for a solution, I have just accepted the drop in quality / flexibility and have had to ignore my preference for using the EXPORT method. I just PRINT to PDF and save myself the bother of waiting for a solution. That said @SketchUp3D_de has recommended a possible solution but I haven’t had time to try it out yet - if anyone else has time to try it and update this thread that would be great.
The issue with dimensions that you seem to have is similar but not the same as mine - I can’t EXPORT any PDF’s, even from a totally blank file with nothing in it. Does it do the same for you?
Given my experience with this, I wouldn’t hold your breath waiting for a solution. Just get PRINT PDF working and save yourself some frustration.
Hope you are at least able to use the PRINT function…