A construction due to Darmon-Rotger gives rise to generalised Kato classes  \(\kappa _p(E)\)  in the p-adic Selmer group  \(\textrm{Sel}(\textbf{Q},V_pE)\)  of elliptic curves  \(E/\textbf{Q}\)  of positive even analytic rank, where  \(p >3\)  is any prime of good ordinary reduction for E. Darmon and Rotger conjectured that  \(\kappa _p(E)\ne 0\)  precisely when  \(\textrm{Sel}(\textbf{Q},V_pE)\)  is two-dimensional. The first cases of this conjecture were obtained by the author with M.-L. Hsieh. In this note we give a new proof of the implication \(\kappa _p(E)\ne 0 \Rightarrow \dim _{\textbf{Q}_p} \textrm{Sel}(\textbf{Q},V_pE) = 2 \)   established in op. cit., and show that the converse implication holds if and only if the restriction map  \(\textrm{loc}_p : \textrm{Sel}(\textbf{Q},V_pE)\rightarrow E(\textbf{Q}_p)\widehat{\otimes }\textbf{Q}_p\)  is nonzero. The present approach is an adaptation of the method introduced by the author, where the case of CM elliptic curves  \(E/\textbf{Q}\)  is studied.