Great questions. Sadly, I don’t have any really good answers for you.
I don’t know of specific cases, but for example I think it is quite common for people to start studying meta-ethics because of frustration at finding answers to questions in normative ethics.
I do not, except for the end of Superintelligence
Many of the philosophers I know who work on AI safety would love for there to be an AI pause, in part because they think alignment is very difficult. But I don’t know if any of us have explicitly called for an AI pause, in part because it seems useless, but may have opportunity cost.
I think few of my friends in philosophy have ardently abandoned a research project they once pursued because they decided it wasn’t the right approach. I suspect few researchers do that. In my own case, I used to work in an area called ‘dynamic semantics’, and one reason I’ve stopped working on that research project is that I became pessimistic that it had significant advantages over its competitors.
I think there’s a steady stream of philosophy getting interested in various questions in metaphilosophy; metaethics is just the most salient to me. One example is the recent trend towards conceptual engineering (https://philpapers.org/browse/conceptual-engineering). Metametaphysics has also gotten a lot of attention in the last 10-20 years https://www.oxfordbibliographies.com/display/document/obo-9780195396577/obo-9780195396577-0217.xml. There is also some recent work in metaepistemology, but maybe less so because the debates tend to recapitulate previous work in metaethics https://plato.stanford.edu/entries/metaepistemology/.
Sorry for being unclear, I meant that calling for a pause seems useless because it won’t happen. I think calling for the pause has opportunity cost because of limited attention and limited signalling value; reputation can only be used so many times; better to channel pressure towards asks that could plausibly get done.