Hi, thank you for your feedback!
The analyze button (top right) will only analyze non-analyzed tracks, even if it will iterate on each track of your collection (and check its state, if analyzed go to next track).
But let's say AUTOGAIN is ON while it was OFF when you first analyzed your tracks: we will analyze only AUTOGAIN for tracks already analyzed, and analyze AUTOGAIN + BPM + KEY + .... for new tracks.
About database sync, we've some ideas