I had exactly the same idea with Weasley Family Clock, luckily I found your post pretty soon, so I didn’t’ have to make this research on my own, thanks a lot. Such shame that they act like that. Beside the fact, that Google Task are not able to show tasks from all your lists at once (!), it’s another big disappointment that I had recently experienced.
Anyway, have you made any progress with the Clock? Are they working?