Updating the post right after fixing the issue on the Nexus 6P. For starters, plug your old computer into a USB flash drive or external hard drive, which typically can cost from 30 to several hundred dollars depending on. However, if this issue persists, you can update your Android OS to fix Android file transfer not responding on Mac/Windows. Then, Android file transfer should work normally.
If both computers are using macOS Sierra or later, place them near each other with Wi-Fi turned on. Step 1.1 – just happened to me on stock Android Marshmallow 6.0 Tap USB for charging for more options and check File transfers to enable it. As Apple explains: If your old Mac isnt using OS X Lion or later, and your new Mac isnt using OS X Mavericks or later, youll need to follow the Mountain Lion migration steps below.
To complete the second step download and install Android File Transfer. Pick up the USB cable that comes with your Oneplus device. If you think that your problem with transferring files is software-related, try connecting your device via USB to your computer, check “Camera (PTP)” and uncheck it again. Let's see a step-by-step guide to transfer files from Oneplus to Mac via Android File Transfer.