If you’re running Lightroom CC 2015.2 (newest release) on a Mac, you may get unexpected hangs and/or crashes, especially during batch export. The workaround, according to Adobe, is to go into Preferences, and in the “General” tab, uncheck the “Show ‘Add Photos’ Screen,” quit, and then re-launch Lightroom. I tested it after experiencing this issue while exporting a 166 image time-lapse and found it to work. Hopefully the issue will be corrected quickly.
UPDATE: 9 October 2016
Adobe has released Lightroom CC 2015.2.1 which appears to fix the hang/crash issue when exporting images.