Had the GPS, tide/date, issue this spring after launch for the season with our Garmin 17x GPS antenna, GPSMap 4208 and 4210. 1999 dates showing.
Installed latest legacy software.
Didn't solve the problem and actually made it worse as the GPS 17x then would not show as a Garmin device, chart showed an incorrect position (with a "?" mark) and no satellites were shown. Also, the 17x software reverted to an earlier software version.
My failing memory seemed to recall (a day later) that during the software update a msg flashed by about 17x software failing to load.
Reloaded the update, and it updated the 17x software successfully this time, and now all is well in chart plotter land (waterland?).
Dates, tides and position (+/- 9.8 ft) right on .