ANDROID WEAR 2.8: UNREAD COUNT BROKEN
It is not specific to Bubble Clouds. Happens to other watch faces too. Google messed up a few things in the 2.8 update. You can read the whole list on reddit:
► https://redd.it/7rpj61
Temporary fix: I hope they will address this in another update soon. Until then you can try to place a Notification count complication: