Apple Watch: Sync with airplane mode on takes a long time to update

### Description

When the watch is in airplane mode (with Wifi and Bluetooth enabled), the sync from the watch queue (Phone source) takes a long time to update with what they have on the phone.

[5504783-zd](https://woothemes.zendesk.com/agent/tickets/5504783)

It might not be a bug or something we can solve and more of a consequence of using airplane mode.

##### User device: Apple Watch Series 4

Start by reproducing the sync from the watch queue with an Apple Watch Series 4 in airplane mode while Wi-Fi and Bluetooth remain enabled. Trace how the Phone source updates on the iOS app, then determine whether the delay is expected airplane-mode behavior or an actionable bug; done means documenting that conclusion or identifying a verified fix.

Written by the indexing model from the issue text.