Also, Album Art isn't updating at all after the first song on a WHA group - but I can force it to update if I toggle debugging and "save preferences", triggering an Updated() and initialize().
[UPDATE: I've been digging into the code. It's fairly easy to understand after you stare at it long enough.
I think the problematic line is 520 of Echo Speaks Device:
if((Boolean) state.isWhaDevice) { return }
This basically makes multi-echo groups ignore updates. Commenting that out seems to cure the WHA groups not updating album/track info as they play. No obvious negative effects... (so far)]
[UPDATE2: This appears to also fix non-group track data updates after being part of a group]