Andreas Mogensen, a Senior Research Fellow at the Global Priorities Institute, has just published a draft of a paper on "Maximal Cluelessness". Abstract:
I argue that many of the priority rankings that have been proposed by effective altruists seem to be in tension with apparently reasonable assumptions about the rational pursuit of our aims in the face of uncertainty. The particular issue on which I focus arises from recognition of the overwhelming importance and inscrutability of the indirect effects of our actions, conjoined with the plausibility of a permissive decision principle governing cases of deep uncertainty, known as the maximality rule. I conclude that we lack a compelling decision theory that is consistent with a long-termist perspective and does not downplay the depth of our uncertainty while supporting orthodox effective altruist conclusions about cause prioritization.
(personal views only) In brief, yes, I still basically believe both of these things; and no, I don't think I know of any other type or action that I'd consider 'robustly positive', at least from a strictly consequentialist perspective.
To be clear, my belief regarding (i) and (ii) is closer to "there exist actions of these types that are robustly positive", as opposed to "any action that purports to be of one these types is robustly positive". E.g., it's certainly possible to try to reduce the risk of human extinction but for that attempt to be ineffective or even counterproductive (i.e., to on net increase the risk of extinction, or to otherwise cause significant harms such that I'd consider the action impermissible), it's possible for resources that were acquired for impartial welfarist purposes to eventually be misused, etc.,
I made some nuanced updates about "acquiring resources for longtermist goals", but they are mostly things like me having become more or less excited about particular examples/substrategies, me having somewhat richer views on some pitfalls of that strategy (though I don't think I became aware of qualitatively 'new' pitfalls), etc., as opposed to sweeping updates about that whole class of actions and whether they can be robustly positive.