Inbox pane opens then hides

Chrome browser (portable apps) version 38.0.2125.111.
Also Firefox (33.0.2) and Internet Explorer 11.

When I view Stash projects pages on my Stash installation, I see there is a new notification : I click onto the little icon, notice the following : the notification pane very briefly opens (I can hardly see the little "loading" animated picture) then closes so that there remains only a "bar" with little arrow pointing to top (such as a closed panel)