FCPX no gpu acceleration on MacBook Pro 2014 15 inch

I downloaded the FCPX onto my MacBook Pro from MAS, then imported my libraries and opened one library on the MBP, the CPU usage immediately went to 100% during rendering process, I checked the activities monitor and GPU history, it seems to me that the FCPX was using CPU for video rendering, the GPU was sleeping the whole time.

The official support page says my MBP supports gpu acceleration - https://support.apple.com/en-au/HT202239#intel .

Did I miss something? Need I to manually enable GPU acceleration?

Thanks!