EndNote X9 - Check for Updates generates WRONG message in macOS 10.12.6 (16G2136) Sierra! For instance, EndNote X9.2 (14655) generates a wrong report:
You are currently running the latest version of EndNote X9. Please check for updates again in the future.
Yet, there is a newer version: EndNote X9.3.3 (15659).
Yes, I found that they require that to be a manual update, because it also converts the library and I guess they want you to be sure you know and understand that, before running it. see discussion in this thread:
https://community.endnote.com/t5/EndNote-General/Endnote-x9-3-updates-converting-to-new-engine/m-p/154004/highlight/true#M32317