I have had the same experience as the OP recently, it is taking more and more effort to get the "facility seats":
The first request was by phone for 1K and 2K PVG-ZRH in May this year, the agent assigned the seats with no problem with a short remark about 2K being a facility seat and the possibility of being re-assigned.
The second request was by phone for 1K and 2K BOS-ZRH in June this year, the agent assigned the seats with no problem with a short remark about 2K being a facility seat and the possibility of being re-assigned.
The third request by phone for 2K PVG-ZRH in August this year, the agent was very reluctant and I had to mention my SEN status, and only after leaving me on hold for a couple of minutes checking with somebody, I was given the seat.
The last request was maybe 10 days ago, again for 1K and 2K on ZRH-BKK and PVG-ZRH, the agent first told me there was no way to assign those seats, and after I mentioned that I have had the seats reserved before (this is the same reservation as in my first call in May, but the date changed and one leg was added), she tried something and came back with a "not possible" again. I mentioned both passengers being SEN again and only then, and after being put on hold for a couple of minutes again, I was given the seats, "but only as an exception".
So it does seem to take more and more effort, maybe some internal LX rule has changed?
