Within the link directory when you create custom fields for each category (great idea btw) there's an option for a checkbox (Yes/No) However, selecting this option only gives you the option to check "Yes", there is no "No" option.
I don't know if it's due to having it set as a "Required" field or not, but there should be a "No" option next to "Yes" and the "No" option should be selected by default IMO.
See here:

Hope to see this resolved soon. :) Thanks!
Something.....something......dark side.....something something something.....complete....