I have 4 hubs in a Production array and also 2 Development hubs powered on 24x7 naturally. (This is to distinguish from the 4 additional hubs that are powered down / retired. )
None of them have a memory leak I've detected. That's NOT to imply there's no memory leak, it's to indicate the other end of the spectrum.. that inherently the hub has very low or no memory leaks. Leaks therefore would be configuration dependent. Your mix of Devices, Apps and Drivers exposes a leak that my mix of Devices, Apps and Drivers does not. And my point there is to say, it's going to be hard to reproduce. Quick resolutions occur when bugs are reproducible, while non-reproducible bugs take much longer.. so long they probably seem like they aren't being looked at.