Steps to recreate

-Fill in connection fields individually
-Click "More Options"
  -Change Read Preference to a new option ("Primary Preferred") so message "You have unsaved changes.[discard]" appears
-Click "Paste connection string"
-Click "discard"
-Expected to see connection string in field to update. It did not.
-Clicking "Fill in fields individually" has no effect but expected to see the other connection screen