M8 won't connect to HTC Sync Manager

Recently I updated my M8 to Lollipop via RUU. Before the update, I backed up my phone using HTC Sync Manager (SM for short) but now that I finished updating my phone, SM won't recognize the phone any more. I tried reinstalling, restarting, and or resetting my laptop, my phone, and SM. My laptop does recognize my phone as a media device player and able to access both, internal and SD card memory. When I connected, SM tries to connect to my phone but after a while a box will appear saying that "Device is unavailable. Please reconnect your device. [4]" Dunno what to do and getting really frustrated with this. Can someone please help? Thanks!

Info:
HTC M8 (ATT Unblocked/Unrooted); Android 5.0.2; Software 4.28.502.1
HTC Sync Manager v3.1.54.2
Laptop Toshiba Satellite; Windows 10; Intel Core i3