Some things you can do to check are:
-Check if it has visibility set to visible.
-Go into debug mode and check if it is being spawned, it may also spawn off-screen.
-Search for the bullet in event sheet and make sure it's not destroyed, moved, etc.
Hope these ideas help, your best hope is to search through your event sheet and just check that nothing is being done to the bullet that you don't want to happen to it.