Page Settings: screwed up page overview if "Vertically" for "Scroll Pages" is activated (MuseScore 3.2.3–3.3RC)
(1) In Preferences–Canvas under Scroll Pages, select Vertically
(2) Open the Page Settings dialog box, where the preview is also displayed in portrait format.
The result is: at default size of the dialog box you see only a part of the page and no miniaturized layout view of the whole page.
Irrespective of the selection under "Preferences-Canvas-Scroll Pages", preview pages in Page Setting dialog box should always be visible next to each other (there is also only a horizontal scroll bar, which is why I assume that the portrait view was also not intentional).