The December 2018 Lightroom updates are now available. Lightroom Classic includes Custom Develop Panel Order, Snap to Grid in the Book module and more. Lightroom CC has lots of little improvements, including a face rectangle in People view on the desktop and Sharing improvements on Android. The Lightroom Queen eBooks are already updated for the changes.
We're hearing quite a number of reports of crashes in LR6.11 and earlier on High Sierra. It appears that Apple made some notable changes in High Sierra that affect Lightroom. The fix is to upgrade to Lightroom 6.12 or later. I haven't come across another reliable one I'm afraid.