Comment by Zak
8 hours ago
Looking at the discharge curve for an alkaline, much of the energy is below 1.2V even under light load. A device that works with alkaline and not NiMH due to voltage is broken as designed.
https://lygte-info.dk/review/batteries2012/Duracell%20Ultra%...
If you need 1.5V / 3V for some reason, you could maybe insert a tiny boost converter from AliExpress (1€, less than 1 cm in all dimensions). I have done that for a string of fairy lights.