Which app does this menu bar icon belong to? I'm talking about the leftmost icon in the bar, to the left of the f.lux icon. Nothing happens when I click on it. And having opened the menu on another item and then navigating to the left or right with arrow keys, will jump over this item.
It's a stupid LibreOffice icon showing up when a new update is existing.

https://apple.stackexchange.com/a/252910/361005