I have spent a few hours around this issue, it also hapened to me.
Spent a few hours mesing around with the key definitions but nothing worked, and got to a point where i said that it was imposible that my settings were wrong and just quit.
So happens that leaving the definitions as they looked correct to me, external freelook toggle sometimes is working perfectly, sometimes it is not and freelook is allways on.
So definitelly it is not a keymap issue, it is certain to be a bug.
Will wait and see is some patch solves it.