Empty tab items disappear

I dont know if this behaviour may also be replicated with other kinds of blocks but when you include a “tabs” block, first thing every user will do is to delete the “Tab 1, Tab 2 …” text and add their own text. But when we delete that “placeholder” text the tab disappears and there is no way to add a new text. When I inspect the code I can see that the tab title code was replaced by “<br data-mce-bogus=”1″>”.