My husband and I have the same phone - Moto G3. I am able to connect with a USB and transfer files/pics to my computer. His phone does not show up at all. Neither does my son’s, which is a Moto E4. Both show that they’re charging when plugged into the computer, but don’t show up in the notifications menu on the phone or in Windows on the computer.
I’ve searched online and have tried many things. I used a different cord, i swiped the notification bar on the phone, but there isn’t a connect option there, I cleared the cache, I unmounted the SD card, my husband tried putting it in developer mode… Please help!