Filemanager doesn't mark selected file, "Filesystem" folder remains closed.
In the backend sidebar click on "Files" then open "Filesystem" and select any file.
"Filesystem" still closed, file wasn't marked as selected.
It would be nice if filemanager shows what file is currently opened, moreover "Filesystem" would also be active (open)
Here are some helpful screenshots where you can find element's classes which could solve the issue.
It is important to say that the same (current object selection within tree) works correctly for "Resources" and "Elements" tabs entities.
Also I've noticed that 2.5.1 version was able to mark as "opened" Filesystem folder icon, unfortunately file was also non-selected there.
MODX Revolution 2.5.4-pl on MODXCloud