Mine works fine . Sorry you may have misunderstood. There is no "latch " or "lock" which is what It seems the OP was asking about.The fuel door has a spring-loaded system which holds the door tight to the body while driving. If yours doesn't work, you better think about getting it fixed.
If there is a concern that the fuel door might get tampered with at some point or you wish to have a bit more protection from car washes, dust/dirt, rain or snow entry, there are a couple things some have used for capless fuel fill doors.