When I try to download pictures from phone to computer, "no pictures found on this device"
Make sure you have choose either PTP or MTP connection on phone. If still doesn't work than try this:
Go to settings>apps and find "media storage" and "external storage" (maybe you'll need to check "show system") clear data for both of them, and then reboot. After device boots wait up to 10 minutes for media database to update and connect phone via USB to PC.