After inspecting my switches and light fixture, I am fairly confident that my wiring matches this image.  If so, the 'bundle' of white wires I see in the first/left switch box are not actually 'neutral', but are 'line', and I cannot use the HS210 in this configuration, correct?

I have tried installing the HS210 in the first/left switch box, but it clicks off and on repeatedly when I turn it on.