This is basically the same problem described in a question from 2014/15 (Why does Writer think I'm printing a Japanese Postcard?) and I’m posting because the “answer” to that question wasn’t really a solution. I want to print some crib notes on a 3x5 index card. I go through the menus to “Format Page”, and set a user customer paper size of 3" wide by 5" long. In the editing layout view it looks great. In the print preview it even looks great. BUT when I hit print and the dialogue with the second preview appears, it has changed the paper to “Japanese Postcard” and the dimensions are wrong. As a result, it prints the top and left of the card off the paper.
The previous “solution” was to blame the printer. That is an not accurate assessment. I am using a Brother laser printer with the manufactuer’s CUPS driver. The driver includes a 4x6 paper setting, a Postcard setting and a Postcard (Double) setting. None of the paper options are “Japanese postcard”. Furthermore, the printer CAN print properly on 3x5 cards in Windows using MS Word. There seems to be a breakdown in Libreoffice where it attempts to finalize paper settings with the print driver, and ends up pulling in a “best fit” from who-knows-where (because it’s not the print driver). I’ve seen some software that will raise an alert that says “This paper isn’t supported, do you still want to use [xxx] instead?” but that isn’t happening. I really think someone should look at the paradigm here for print media verification and settings because my guess is that, if almost 10 years from the first time someone here reported this problem, a fix hasn’t been incorporated, then the issue requires some fundamental examination.
Also, interestingly, just like the other person who raised this concern in 2014/15, the 3x5 media size does properly format in the second print preview box for my HP color inket printer – my non-default printer – which is also using a CUPS driver. However for obvious reasons I want to use my Laser Printer for these cards.
My version of LibreOffice is 5.1.6.2