Well I don't use Windows so I can't help you there, but may I suggest a solution/workaround that works on most platforms(windows,linux,mac).
On your phone install Airdroid from the playstore. Then in your browser on your PC open the airdroid website. On your phone open airdroid and scan the barcode on your pc screen with the airdroid app.
This will connect your phone to your PC wirelessly and you'll have access to both your internal & external SD from your pc web browser and in turn your DCIM. I've been using airdroid for quite a long time and has never failed me.
Only other thing I can think of is a possible file in your DCIM folder blocking access to those images. I don't remember the name exactly, but I came across it a long time ago. I think it's called nomedia, but not sure. If there, simply deleting it or renaming it and rebooting should fix it.
Good luck.