Tested in version 4.17 in both Harvard and Scholars Portal Dataverse instances. Tested in Chrome (78.0.3904.70) and Firefox (70.0) on MacOS Mojave.
When creating a dataset and entering metadata in Google Chrome, clicking on the name/label of the subject makes the subject box disappear. The issue does not happen if you only click the checkbox.
The problem starts at the "Earth and Environmental Science" subject, which causes the box to partially collapse. Clicking subjects below "Earth and Environmental Science" will cause the block to disappear completely.
Clicking on the text label for "Earth and...":

Clicking on any text label below "Earth and...":

The bug does not occur in Firefox; other browsers were not tested. Screenshots above were created from the Harvard instance.