I’ve been wrong saying
So it seems to be a bug.
Of course it’s not.
The parameter [tt]&startItemTpl[/tt] by default is this:
<h2>[[+wf.linktext]]</h2>[[+wf.wrapper]]
So if you set [tt]&displayStart=`1`[/tt] without explicitely giving a [tt]&startItemTpl[/tt] you will get this headline.
Obviously, in the original WF call, [tt]`FALSE`[/tt] is token as [tt]`1`[/tt] and so the default [tt]&startItemTpl[/tt] is applied.
Solution: Or to set [tt]&displayStart=`0`[/tt] (the default value, so you can leave it out as well), or to define an own chunk for the [tt]&startItemTpl[/tt] , f.e. containing just [tt][[+wf.wrapper]][/tt] .