2 Desktops on 1 .docx

My colleague and I use Libre (L) to open the same .docx. She saw some blank pages between pages and different alignments. Would you please tell me the reason(s)?

You have tagged this common but talk about .docx, are you sure you don’t want to re-tag it as Writer?
If you are both working on the same document in LibreOffice then you should both work in native format, .ods. You can Save a Copy as .docx if necessary for export to others but don’t edit that copy as multiple conversions can do strange things.

  1. Different fonts; make sure you both have the same fonts
  2. Different view; at the bottom right in the Status bar are an icon of a page (tooltip Single-page view), an icon of two pages side-by-side (tooltip Multiple-page view), an icon of two facing pages (tooltip Book View). The person who can see blank pages is using Book View which I would recommend.