[BATT_IS_CHARGE] is working on the actual watch, but not in Preview (emulator).
It works in WFS 1.3.8 bèta. Which version do you use?
Same here, that’s odd. Maybe it’s because I use it with battery conditional line? or it has something to do with JSON?
I use a JSON for low battery warning, its battery conditional line is set to be visible between 0 to 10%. Then use ([BATT_IS_CHARGE]==1) ? 0:100 to hide it when charging is on. It works on watch, but Preview doesn’t hide it when the charging option is checked.