After upgraded to DSM 6.2.2 and moments 1.3.2, the face recognition is empty , and concept category only has child.
I found thus shoud be a bug of photo detection plugin.
So, there is the way to fix it:
1. enable SSH, and disable Moments.
2. replace /var/packages/SynologyMoments/target/usr/lib/libsynophoto-plugin-detection.so with my attachment.
3. enable Moments. (maybe need to reindex.)
everything is fine.
Enjoy~
libsynophoto-plugin-detect