Most home printers have a nonprintable area, but its size depends on the model, paper and mode. The studio starts with 10 mm margins as a practical layout setting, not a guarantee for every printer. Check your printer manual and test before reducing them.
Find the cause
First compare the PDF paper format with the loaded paper. Next check scaling in the PDF viewer, then in the driver. If only the image edges disappear, inspect crop mode and borderless expansion. If only part of the sheet is missing, check the printer’s nonprintable margins.
Before you print
Use Actual size or 100% in the PDF print dialog. Match the paper format and disable any further resizing in the printer driver. The preview shows the PDF layout, not a guarantee of your printer’s printable area. Start with ordinary paper and measure before using photo paper.