0.0.0.19 sensors worked. 
Testing humidity, which is easiest… took 3 sensors and cupped them in my hands and exhaled. Notifications were immediate (less than 2s) so it’s obvious that these sensors “push” based off some delta threshold value.
App display of 0.0.0.19 events was similar to 0.0.0.21 events, it took 2 minutes for this to populate:
And about 2’15" for this to populate:
Using production app for Android v2.29.0 (114).