Well I remember seeing a youtube video saying that it’s because itunes blocked some data when you sync your apple products, so you may try to change some settings to make them unhidden. Unfortunately I don’t have that video right now. but you can google your question “how to transfer photos from iphone to pc” to find that video. Oh and remember to choose "video" tab on the left side to screen the search results, it will help a lot to find the more exact answers.