I'd say your first problem is that both humidors aren't nearly full enough. It order to help stabilize humidity, the general rule of thumb is at least 75% full. This might sound like a marketing scheme to constantly buy cigars, but it really matters. That's too much air to be humidifying.

Your second problem is a bad seal. Go into a dark closet, place a flashlight in your humidor and then close it. Wherever light is leaking, air is leaking, too. This likely first began to be an issue in winter because not only does ambient humidity dip drastically in the winter, but wood also contracts, likely making the leaks in your humidor worse. You should see the 105-year-old wood floors in my house. In the winter, you can slip a nickel in-between many of the floorboards. They then seal shut in the summer. There are ways to fix a leaky seal, but I for one am way too lazy to mess with that stuff. I went full tupperdore long ago and will never look back. If you can't live without the look a wood humidor, buy a big one and just stick a tupperware container inside of it.