Still trying to get a handle on this beast, playing with various controls. Here's a snapshot with default settings and then after auto is invoked. Default appears ok, just a small bit of clipping, but unless I'm missing something something is wrong with auto.
'Auto Tone' is simply not good enough to bother using, IMO. (not a big deal for me, since I prefer to "manual" tone anyway, still...).
PS - I have seen this over-darkening behavior in the past which I believed was due to a single overextended channel, which for reasons I don't understand, was not shown in the Lightroom histogram, but you can see it in the histogram of the Mfr. software.