Yes, any new pages opened now reappear when I reopen opera.
Yes, adblock is enabled. Icon in upper right of window is now dark, not the same as before.

Opera froze; after restart, the previous session/tabs did not reappear, even though they always have before after restart. Also, the adblock plus extension is not working - when clicked or right-clicked and then 'options' selected, it says this website is not found.