Sync stops if app isn't in foreground

Been meaning to ask this for a long time. Why won't the app sync in the background?

To clarify:

1. Open app. Sync starts.

2. Switch to another app (short attention span, want to check the news while the watch syncs). Connect is still open but not in foreground.

3. Sync stops when in background. Seems to be somewhat progress dependent - it seems to finish if the progress is at least 3/4 done before changing to another app.

Any ideas?