They never talked about it after v2.1 came out, just that it will come in time (especially not promises, they never make promises anymore), they have never talked about it being in v3.0.0
They are still working on it, and it wil come when it is done, or do we rather have corrupt backup possibilities.
But don’t expect it to be done soon, i think we will see the zigbee rewrite before.
that is a mis understanding of An app that has improved presence detection from before that update, not the Homey app itself
please check your power supply (and try a different one with at least 2A of 5V output).