Just FYI: I think installing the license plugin + the watcher plugin requires a full cluster restart. A rolling restart will leave you in a yellow state when you try to restart your nth node, where n is the minimum master eligible number. Restarting the remaining nodes resolves this.
If you are installing Shield, this important detail is noted in a callout in the docs. It's not mentioned in the Watcher docs, but I believe it applies here, too.