Android 5.0 Lollipop device not detected via USB When the device is set to use MTP, neither Windows, nor ADB will detect the device when connect via USB cable. I have tried multiple cables, in multiple USB ports. I have not tried other computers yet, as this is the only one that actually has the driver installed.

Disclaimer: I am running an Unofficial CyanogenMod 12 build of Android 5.0.2

Device : LG G3 (LG-D855)
Android 5.0.2 CM12-Unofficial-20141228
Google USB Driver: Installed
USB debugging: Enabled
PC: Windows 8.1 Pro Update 1
No one, except me, has reported this as an issue in the XDA thread. 

I have been unable to get my PC to detect the device via USB since I first installed CM12, which was around 11/10/2014.





If i change to PTP, Windows will detect the device, as will ADB. But Windows will only let me access the internal storage, and Camera folders.
After a couple of days of digging, I found the solution to this issue. 

I opened up Device Manager. My first problem is I was looking for Android Composite ADB Interface, which is what it usually is called. I started looking harder. When I noticed ACER Device. My machine is not an ACER, nor do I have any ACER devices attached, or so I thought. I expanded that group and found ACER Composite ADB Interface. 

These are the steps that I followed that got my ADB working with my device. YMMV.




Download the latest USB Driver from Google
I right clicked this device
Uninstall


You may need to reboot after. I did.

Open device manager up again


The device may identify differently, and will probably have a triangle icon.

Scan for hardware changes
Right click the device again
Selected Update Driver Software
Clicked on Browse my computer for driver software
  
Select the path to the drivers that you downloaded at the first step, check the "Include subfolders"

Let it install
Open a command windows (I had to open as administrator)
Run the following:  


  adb kill-server

Now run:  


  
    adb start-server
  

Finally run:  


  
    
      adb devices  
    
  

Profit!