Maybe someone here has that fan, but the problem is that Panasonic has over 30 different “Whisper” models. As @harjms pointed out, he has had success with the WhisperChoice in the on/off mode, but other have had issues with the WhisperGreen model.
I don’t think the WhisperCeiling has been discussed, but the fan issues have been discussed here:
And scattered starting here: ZigBee Fan Switch | Project Zephyr (Blue Series) - #572 by signbit