Merge Academy Not regenerating energy

I completely understand and relate to your frustration. My energy has not been replenishing correctly either, and you will find countless people on here with the same issue.

The problem seems to be that the energy switches to 0 or whatever value you had previously when it regenerates to 100. Therefore, the only temporary solution aside from just leaving the game open to accumulate energy is to stop the meter from reaching 100. This requires some more frequent check-ins and would certainly not be conducive to many people's schedules. However, try using the generator a few times while you have the game open & then check back in an hour or so. You should find that you have energy you can use.