Are you actually adjusting the offset to what you believe it should be for the particular SDR device or stick you're using? I'm going to assume you did so, here's what I just checked and confirmed with a brand new fresh untouched install I just made, haven't been doing some SDR stuff for a while, for the record.
1) installed the Zadig drivers (again, this is a fresh install of everything, recently redid my Windows 7 install because I got a new laptop
2) installed SDR-Radio v2 and then grabbed the RTL-SDR drivers needed for it to see the RTL stick from:
SDR-Radio V2 RTL-USB | AA5SH (the 64 bit drivers) and copied them to the SDR-Radio installation directory (also dropped the license key in the install directory too)
3) Start up SDR-Radio and pick a frequency (I too have the National Weather Service at 162.550 so that's what I chose). The RTL stick I'm using has a +56 PPM so I know the default is set for 0. Upon tuning to 162.550 I got the results in the first image below which was expected since the PPM hasn't kicked in yet. I clicked Radio Configuration to bring up that dialogue so you can verify it's nowhere near centered on that frequency (as you're experiencing).
4) I then adjusted the PPM accordingly to 56 PPM, clicked OK and then... nothing happened. Sometimes, and I don't know why, PPM changes are not immediately enabled, and for some other reason I can't explain shutting SDR-Radio down completely and bringing it back up again
still doesn't enable the PPM change as noted by the second pic below.
But I found a solution that worked for me so hopefully it'll work for you.
5) With the PPM adjustment made and the Radio Configuration dialog closed (by clicking OK on it), click the Stop button to disable the RTL stick. Don't shut down SDR-Radio, just kill the RTL stick itself by clicking the Stop button.
6) Enable the RTL stick by clicking Start and voila, the PPM adjustment now kicks into action and you get centered as you should be (as the third pic shows) and everything works as expected.
I just tested this process 3x in a row and got the same results each time so I hope this gets you past that nasty little issue.
