Reaper stopped hiding tracks in a mixer panel

[111]

For some reason tracks stopped hiding when I click on a folder icon on the track in mixer panel. Speaking about those horisontal tracks which are to the left, they can be hidden as usual. Could you advise how to fix it, if it`s possible? I need tracks to be hidden in a mixer panel as they are in folders.

[esosotericmetal]

Click on the Mixer menu and make sure "Clickable icon for folder tracks to show/hide children" is checked.

[111]

Thanks, I already guessed. But I didn`t understand why Reaper unchecked this option by itself) Rise of the Machines 0_o