How to fix?
This question has been asked and answered various times already, for example Won't print portrait This is an Letter Sized paper problem. Define a special paper size a fraction different from Letter as a bypass.
… and wait for 5.4.4 and 6.0, where it’s fixed.
How do I define a custom paper size/.
This is not an answer, this is a WORKAROUND for a problem that has persisted for at least 2 years and 3 Libre Office versions
@BadBadDog : it looks like people don’t try to read. When people ask what to do on some problem, it is the answer to point them to a confirmed bug report, because what else answer do you expect from a fellow user for a problem of the program? Did you fix it? no? then do you expect another user like you to fix it?
Even more so, when the bug report tells you when it is solved - in this case, in 5.4.4.