I can't speculate as to the problem in your case, but I've never used a BT mouse nor have I ever heard of one that didn't have some intermittent drop-out of response problems on any platform, Mac or Windows.

IMO, BT is great for syncing data, pretty good for a keyboard, but terrible for a mouse.

My next mouse will likely be a Logitech VX Nano (or something similar but not yet released if I don't get it soonish). I have found in the past MS mice more responsive, but recent models have not lived up well physically to regular use.