macOS 10.13.3, Endnote X8.2. Unusable as is. After a short amount of time ANY activity causes the spinning beachball. One CPU pegged at 100%. Looks like there is a combination of issues. Poor software architecture, an activity that should NOT block the UI, and the underlying bug that causes the issue (memory leak and something spinning on a condition?). After some time the app crashes altogether. This is seriously amateur stuff, any first year CS student can do better than this.