Dane wrote:But new photos are not displayed at the top, but further down.
I see that photo's date is
"01 August 2019", and since you have set to sort by DATE, the layout is correct. When you use DATE sorting, X3 will the images "dateTimeOriginal" (EXIF), which is when the photo was taken, and which is preferred in most cases for date sorting (as opposed to sorting by server-creation date, which might be ranom).
If you simply want latest uploads to appear on top, then why not use CUSTOM sort? When using custom sort, latest uploads will appear on top (until manually sorted by drag-and-drop). If you change to custom now, you may have to drag your images into preferred order, but new uploads will always display on top.