Eclipse Community

I'm experiencing the exact same behavior as this one:
https://www.eightforums.com/threads/pinned-items-disappearing.56410/

This is about the menu when doing a right click on the Explorer icon in the taskbar. And not only the folders items vanish from time to time -but one- but now I can't pin some of them anymore, when I click on the pin icon nothing happens
Any ideas ?