I am working on a magazine and use CC Libraries extensively for titles, graphics, and magazine fonts and colors. I open the panel and it loads, no connection issue or error messages, but it's just blank, I can hover my mouse over items that should be there and the mouse will change to the "click" version, so I know everything is there, it's just not displaying.
Go to the CC desktop app > "gear" icon > Preferences > General. Log out and log in again with your Adobe ID.
If the above suggestion does not work, then try re-installing InDesign.
After uninstalling ensure that the folder C:\Program Files\Adobe\Adobe InDesign CC [Version] goes away.
On Mac you would find Adobe InDesign CC[Version] in the applications folder. Once you uninstall this folder should go away completely.