The following happens in 7.0.5, not 6.4; I have both installed in separate directories. I always keep the last version installed just in case. System is Linux, Devuan ASCII. 64Bit Intel 8 core processor, 16GiB of RAM.
In any case, in office, with the document page set to letter, the print page shows:
Page Layout
Paper Size
Letter 71.97in x 93.13in
The document prints just fine on my Canon MF244dw but the crazy paper size is disconcerting. Note, this problem appeared with the upgrade to 7.0.5, it was not present in 7.0.