See attached screenshot - Anyone recognize this kind of thing?
Is this some sort of blue lot bug?
Never had something like it before. I saw it first after editing a lot (in EIG). It's only this lot, and it only looks like this when it's not rendered in detail.

It is a LOD (level of detail) bug/issue. I've had it happen to me before, while in CAW and EIG. I'm not sure how or where that LOD info is stored, but when I had that problem, deleting and replacing the lot in EIG did not help. To fix it, I had to delete the lot in CAW, replace it there, then put the build back in in EIG. This was in a world that was previously packaged and I had to extract, and it was ages ago. Someone who has used CAW recently might know a better way.

Previously packaged world, that is true in my case! Thank you for the helpful insight, I will try your method and report.