In Convertigo Studio, a JS plugin is used to perform syntax coloring in JS code.
One feature of this plugin reorganize folders and sub-folders in Project Explorer view, sometimes making access of the folders content impossible.
In Convertigo Studio, click on the "Project Explorer" tab.
Click on the "View Menu" icon
, then choose "Customize View…"
Click the "Content" tab then unckeck "JavaScript Elements" and click the OK button.
Your folders structure is back to normal and all accessible.