I am using QGIS Atlas to export my work into PDFs. I have created a support polygon layer, which contain rectangles and I use this layer as coverage layer in QGIS atlas. My problem is that I don't know how the pagenumbers work. It change the page order when I update a feature in the coverage layer. For that reason I activated the sort by option, and used the autoincrement id of the coverage layer, but nothing had happened. It looks like the atlas is using kind of time metadata for page numbering. Is there any way I can fix this?
It's possible that the issue only appears with autoincrement fields. Try creating an integer field containing the desired page number.
If this is an issue in the latest QGIS version, it should be reported as bug.