Copy not allowed

[MSpagni]

In a long list I have a group of files (apparently nothing special in their names or directories) in the left pane and nothing in the right pane.
Normally I click on the arrow in the leftmost column to copy that block of files to the other directory.
In this case the popup always says: "... Deleted 10 items ... Click here to select this block"
Why just "select" and not "copy to other directory" as usual? The arrow appears (as it should) but is ignored by the mouse.

If the "block" is composed of a single file all is ok.

If I select the files and, opening the local menu with the left click, I click "copy to other directory" then the copy is done.

That problem exhists only in the left pane. The right one is ok.

[psguru]

The tooltip you described appears if you move the muse below the arrow button. What does the arrow tooltip say? Could you also post a screenshot?

[MSpagni]

The arrow is completely ignored by the mouse.
The tooltip is the same all along the vertical bar AND on the arrow.

[MSpagni]

I must have overlooked something. The effect is not so easy to reproduce.
But yesterday I got it four times in a row!

[psguru]

Please let me know if you find out how to reproduce this.