I found a way partially around this problem. (At least a work around on my setup.) It is clumsy, but here's what I do. I jump to internal view, then tap "z" for zoom, then use the "[" and "]" keys to zoom in and out. Then I jump to external view. Now field of view is zoomed (and I can toggle it with "z"), and I can use the distance-zoom slider for a limited range of distance. If you touch the FOV zoom slider, however, it will jump back basically to unzoomed state no matter what the slider is set to, and you can't get any zoom back by playing with it.
I hope they fix FOV zoom in the next release, but until then, that's how I've been dealing with it.