Unexpected behaviour with Colorbox library

Issue

• When attempting to update the version of JQuery in the developer portal from v1.7.1 to v3.5.1 the developer portal, shows a floating "close" button with no functionality.
• The majority of the JQuery usage is in the bundled 3Scale.js file, this also includes the Colorbox library (v1.3.19).
• Is there an up to date version of this file using recently released libraries, or failing that, is the Colorbox library necessary to the functionality of the developer portal?