This extension was always clunky but since few weeks, it does not work at all. I highlight pages, they appear highlighted and when I revisit them, they are gone.
Few dozens notes went to waste before I realized all my work is not being saved.
I had "Professional" user tier mostly for assets fetching but this too stopped working.
Diigo prides itself in staying online for 10 years now: being online is one, keeping your product working in ever-changing Web is another.