It could certainly be USB related. But not using a hub isn't very practical. I have used this particular EFW2 for over 5 years with at least 3 different hubs. I must admit that this issue may have started around the same time I introduced a new powered USB3.0 hub into the mix. I can't remember for sure, but I do think it started before that.
It seems like if it was USB related it would happen more often. As it is right now I can go hours with multiple filter changes and then it will randomly fail to report a filter change. I simply can't see a pattern or trigger that causes it.