Not a crisis, but documenting for the record.
I still use a PR511 to turn on my exterior lights at dusk (yes, real dusk!). I have the sensor set to turn on units 1, 2, and 4. All three turn on correctly, but the WM100 only records unit 1 in the log, and most importantly, only updates the on/off status in the app. No sign of units 2 and 4. A swipe refresh does not work. The WM100 apparently never saw the last two commands.
So, it appears that the "simultaneous" nature of three unit "on" commands is an issue for the WM100.