Jumping to page 1-bug replicated!
Ok, now i have found how the error jumping to page 1 when turning pages, instead of going to the previous page can be replicated:
1. Open PDF
2. Go to PAGE SETTINGS -> set a "Universal Manual" margin
3. Go to READING -> choose a SELECTION ZOOM (I don't know, if it works with all zoom settings, but i tested it with two and three column PDFs)
4. Go to READING -> Switch to PAPER MODE
5. Now, when turning to the previous page, the reader jumps to the first page of the PDF.