Cameras won't blend in timeline, what am I doing wrong?

I've watched several tutorials but I must be missing something, overlapping virtual cameras on the timeline doesn't blend them, it' just moves the position of a hard cut. I never get the diagonal line blend I see everywhere else. What's the trick I'm missing here?

I've tried holding down alt, shift, crtl (the last one does some ease in/out but not actual blends)...