As far as I know (read), this is quite the opposite, very low humidity seems to induce more static issues, it’s even been recommended to spray a mist of water on the stock to reduce the likelihood of disconnects in those situations.
Do you have a trim router, if so check its brushes ? I remember @WillAdams mentioning that sudden disconnects after a long period where everything is fine, can be due to brushes wearout
Next-up I would try either isolating or connecting the stock to ground to see if it changes anything. The good news (…) is that your problem seems to be repeatable easily, so there’s hope to pinpoint the source of disconnects quickly.