Hi...
No, it's not what you expect from overflying a ground based Navaid.. It's literally an angle offset error. First time I noticed it I was tracking a VOR radial outbound and I realized I needed a very large track correction to keep the HSI needle centered. It was acting as if I had a 100 knot crosswind. Then I did a few tests flying direct to a VOR inbound with the RMI 1&2 VOR needle, the HSI and the #2 OBS all set to the VOR. I noticed that any needles on the #2 nav would track the VOR correctly, but the needles on the #1 Nav were pointing roughly 10 degrees to the left and the closer I got to the VOR the bigger the error. It's almost like if the #1Nav radio was tuned to a phantom VOR that was always left of the one that it was tuned to. I was backing this test up by using the default MSFS VFR map.
Also, the NAV 1 DME was intermittent past 11 miles.. I could listen to the DME on the audio panel as a strong morse signal, but the DME indicator was blank. This was while tracking a back course localizer where the fixes had DME references out to 30ish miles from the localizer.
But the good news is, I just reinstalled everything associated with the King Air, including FSUIPC, TDS GTN, The Caravan and the 850 which I just bought last night, making sure to install the King Air and the TDS last and it appears whatever it was is now squashed. I kinda wish I had reinstalled things one at a time so I could at least find the culprit, but this beats any longer process off troubleshooting.