I would suggest collecting some more information on on the OP’s 2 switch mode power supplies as well to recreate or explore this issue. ?
Two low cost SMPSUs in a row may mean strange distortions of the supply waveform in between them and odd current flows at frequencies not seen in normal operation. ?
On the face of it a SMPSU should react quicker than a linear PSU with an ‘anti spike’ capacitor in the voltage monitoring circuit ?but both can enter unstable or oscillation and failure modes if the loop design allows it and some aspect of usage provokes it?
Bruce Akhurst