STEPS TO REPRODUCE 1. Open a PDF, which was e.g. unfortunately scanned up-side-down 2. Rotate the page by 180° in Okular 3. Hit "Save" or "Ctrl + S" to save the change 4. Close Okular 5. Open Okular and the just rotated PDF OBSERVED RESULT The PDF is orientated as before step 1: up-side-down EXPECTED RESULT The PDF keeps the orientation set in Okular
Rotation in Okular is purely for viewing while in the app, not actually editing the file itself. You'll need to use another app for that.