How to create group for links under particular subheading

Steps to reproduce

I have a kanban markdown file that looks like this

For your convenience, I pasted some lines:

condyle

  • [[AO_2016_Orthodontics is temporomandibular disorder–neutral]]
  • [[Projects/前伸下颌汇总/md/BOH_2020_3D assessment of mandibular skeletal effects produced by the Herbst appliance]]

Did you follow the troubleshooting guide? [Y/N]

yes

Expected result

The notes under this heading should turn to the color as the group.

Actual result


It seems that nothing is recognized.

Environment

Obsidian 1.6.6


Additional information