I had an issue with the original Apple Magic Mouse that would not work correctly with NiMH batteries but work fine with disposable AA. The mouse would be fine for a few days then randomly stop working; using fresh NiMH would revive it again. I assumed it was due to 1.2v vs 1.5v but perhaps that particular mouse (or all Magic Mice) was just bad.
I have an acurite 5in1 weather station running on eneloops/laddas. It whines about the batteries being low but runs for about a month in any conditions. I just rotate and recharge them at the start of the month.
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%...
Apple sold their own NiMHs (actually rebadged Eneloops) along with their own AA charger to go along with the Magic Keyboard/Mouse, so my bet would be on a faulty device. https://en.wikipedia.org/wiki/Apple_Battery_Charger