same here on Mac.
so I tried this and it worked for me. ymmv
renamed Opera Beta.app to "Bad Opera Beta.app" app (in apps dir)
removed shortcut from desktop
downloaded fresh offline Opera Beta dmg from Opera.com
installed fresh Opera Beta package offline
opened fresh Opera Beta app and.... lucky! All my data was preserved
including my bookmarks, settings, plugins! I went through settings to make sure it was what I wanted.
Then I renamed the new app to "Opera Beta 68" just for reference
don't know why this worked .. but it did for me. whew!