When you start a puzzle in Bonza Jigsaw (and this is with every puzzle in the game) you’re only given 2 pieces. Once you move them around and figure out how those pieces fit together, we give you a few more pieces... and then so on and so forth. By rationing the pieces into portions we’re clearing up a whole bunch of room on screen so you can actually see what you’re doing.
Some players have said they prefer to see all of the pieces at once, we are adding an option to enable this and it will be available in the next update (June 2018). Thanks for your patience and understanding.
Here's a video that explains it further.