+this has just happened to me. I lost a day of rain (no rain for 1.5 months here!), so I replaced the batteries with known good lithium. I have 2 gw1000's, both are not seeing it, even after attempting to re-register the sensors. I factory reset 1 of them to no avail.
It's just not broadcasting anymore. I run rtl_433 on the side and I can see all sensors broadcasting, except the wh40. I am at 11 months and 9 days since purchase. I've contacted them on ecowitt, we'll see if they have any ideas on what to try next.