Multiline block in mindmap with markdown style doesn't work

Question

For this code multiline block is placed in the bottom of diagram: 

@startmindmap

* abc
 * bcd
 * dbc
  *:
it doesn't work
;

@endmindmap

 But, if you add non markdown syntax it will works:

@startmindmap

* abc
 * bcd
 * dbc
***:
it works
;

@endmindmap