People get hypnotized into believing things. Sad, but true. Almost everyone says solar magnetic activity is detrimental to dowsing. The Stargate Project by the US govt concluded this fact. Can't recall but one of the books I read about it think the guy's name was McMoneagle said solar wind over 600 kps (or maybe 650, can't recall) their accuracy dropped off. This program had the most talented people in the country and strict protocol. Be careful you don't get hypnotized into misinformation. I don't know but I think some Dell Winders hater started the misinformation rumor. Like Pres. Trump, Dell was always flushing out the swamp and some people didn't like the truth being known about them. And it's not just dowsing/locators--gold nugget hunters have said their metal detectors are affected by solar activity, too.
Signal Line, do you have any links or anything to support this? Wasn't the Stargate Project investigating psi ops? What does that have to do with dowsing? Dowser says that he can only dowse when the solar wind is strong.
I could see geomagnetic activity affecting a metal detector but it would have to be really strong. Magnetometers are severely affected, even in everyday use when there isn't a geomagnetic storm. You need to have a base mag to measure the diurnal changes which you subtract in processing.
It seems that you and Dowser both believe that solar activity has an effect on dowsing but in opposite ways.