I have experiend with one or two different of the childrens BT mouses that they stop working after a few minutes in Linux Mint, but found out that I have to hit left (or maybe it was the right button) mouse button to get them working again a few minutes.
I think it is due to powering down the mouse.
low-energy - Isn't it just Bluetooth LE (Low Enegy) - can be Bluetooth 4.x.