Why can't I upload ALL my live Apple photos to my windows PC
I would suggest that they are in iCloud. Can you tap Settings > [your name] > iCloud and check if Download and Keep Originals is checked? Here is Apple article just in case:
https://support.apple.com/en-us/HT204264

If not, check it and leave the device for 3-4 hours with a robust Wi-Fi connection while photos will be loaded from the cloud (there is no progress bar). After this, check if you will see the photos.

If you still can't see them, do you use any cloud or streaming service for photos? Also, you just connect the phone to PC and open the DCIM folder, right? No iTunes or 3dparty software?