And I take it you don't have an actual physical scanner to use to verify things, either. The simplest answer I can give is this: if you don't see activity in the spectrum or waterfall on the frequency or frequencies where that system should be
and everything else seems to be working just fine (the other digital systems, the NOAA weather, etc) then that system isn't broadcasting on those frequencies as expected and something has changed, or your RTL stick and SDR# just don't like you very much.
Not sure what to say in your situation other than to verify the frequencies yet again as well as you're able. The spectrum doesn't lie as it will display anything in terms of a radio frequency transmission in progress when there's one to detect, so if there's nothing shown then there's simply nothing there at all on the given frequency or frequencies you're attempting to monitor.
You might consider trying another SDR program as well, like SDR-Radio, HDSDR, etc and see if you get exactly the same results. Might not hurt to reinstall SDR# itself too - I can't even begin to tell you how many times people (including myself, actually) have or have had issues with something that simply cannot be solved with respect to things like this newfangled SDR stuff and nearly given up on it with bad results, but then I figured why not scrap it all and start over again and miraculously things do work the second time around - and sometimes the third, fourth, etc.
Can't hurt, right?