QMK Layers

Here's something I just figured out; maybe someone will find this and it'll save them a few days of struggling.

QMK momentary layer switching only works forward, to higher layers. Your momentary layer has to be later in the layer series: you can switch to 10 from 9, but to 4.

But not completely, and that's what threw me off. I'm not clear when it works like this, because sometimes you'll get a key that does come through, but to have it work reliably, have your momentary layers later in the layer series.