Mysterious absence of preferences (no Xmarks icon in the toolbar of Firefox) Rated 4 out of 5 stars
– the first version of Xmarks supporting WebExtensions and e10s.
A first attempt to update from (legacy) 4.4.1 to (experimental) 18.104.22.168a failed, silently and inexplicably; the end result was no Firefox GUI to Xmarks so I gave three stars. LastPass support ticket 6101942.
A second attempt succeeded – there appeared an Xmarks icon in the toolbar of Firefox – so I raised my rating to four stars.