To dream of a jigsaw puzzle represents a multi-faceted challenge or problem that you need to solve in your waking life. Trying your hardest to slowly get something to work or make sense.
To dream that pieces are missing in the puzzle may reflect a waking life situation where you don’t have all the facts needed to make an informed decision. Feeling that something doesn’t makes sense yet, or that you are missing something. Waiting for an answer that makes sense.