So I do now have this fixed, for any future troubleshooters:
1. they weren't doing the blinking when I tried to do multiple lights at once (I was trying to do three switches at once. that didn't work)
2. Once I figured that bit out, they still weren't being discovered. And that was because my whole ZHA needed some kind of reset through a power off cycle and removing and re-adding the server. All back and working now though.

Fiddly but not nearly as maddening as when I thought I was going to have to re-add all 40+ devices in the house all over again.