FYI, and it may or may not be relevant to this case, I did have a rather similar problem with preview, described in this thread:
https://www.mobileread.com/forums/sh...d.php?t=360394
tldr: the solution is described in post #18 of that thread, and involved preview adopting a default font that was a foreign font. I deleted that font, and from then on all was well. Details in the link. It will also show how to use the "inspector" in preview to see what may be going on.
HTH
Albert