It seems that there is currently a bug when packageMode is multi that nullifies descriptions of each class into a rather excessively large string.
Specifically, it seems that it starts at the first description in the document and ends at the first constructor it encounters. If there are no constructors, it leaves it empty.
Here's an example (querystring and Worker Threads properties can be ignored): https://gist.github.com/bnb/bcc9394cfd81bd61ffdb9b3d303b799b