Inconsistent behaviour: After pushing Validation not results are shown

[andreasm2]

When I go to the toolbox-link, select an area and push the validation button, the toolbox automatically switches to the "load results" area.
If I switch to layers and/or the selection area and again select an area and push the validation, the toolbox doesn't switch to "load results" and no results are displayed.
(Firefox 56 and Chrome, Windows 7)