(en) Until recently, to assert at the same time both an adhesion to the Marxian paradigm and a rejection of the labour theory of value would have been considered a sort of blasphemy. A pathbreaking iconoclast in this respect was Joan Robinson, although she did not really speak from within Marxism. For her, value was blatantly a metaphysical concept with no operational content.
De Vroey, M. (1981). On the Obsolescence of the Marxian Theory of Value : A Critical Review of Lippi’s Value and Naturalism in Marx (Working Papers Institut des sciences économiques 8109). https://hdl.handle.net/2078.5/278835