You display profile may be incompatible with LR but not with other programs. To test that, try setting the profile to sRGB as described in this article: How do I change my monitor profile to check whether it’s corrupted?. It looks like you have a serious investment in cameras and software, so spending a very small percentage of that on a calibrator is quite worthwhile.
Yes, setting the monitor profile to sRGB did the trick, appearance of images is now indistinguishable, to my eye at least. Which leads to a question why this works? What I had as default profile is named for the monitor, so I'm assuming it came with the driver for it. I'm guessing for some reason Lightroom doesn't support that particular one. And am I losing color accuracy by switching from a model-specific to a generic profile? Do I need to recalibrate?
In the past, some display manufacturers shipped profiles that were not entirely standards-conforming, and they trip up LR and other programs. Also, I believe that LR silently fails when presented with version 4 ICC profiles, but I'm not sure about that. Regardless, this is a fairly common situation.
While you could use the "by eye" calibration built-in to Windows, experts say that results in profiles that are pretty random quality. Your best bet is to spring for a calibrator.