On Vivoactive 3 firmware 7.00, data-driven watch faces almost never update.
The issue has been observed with the weather functionality in bine8x8's watch faces, xDrip+/Spike Watchface, NightscoutWatch, etc.
Based on developer reports, it sounds like the requests are made but the callback is almost never called. On my device, the issue has been present for 2 days, and of the last ~600 polls I only noticed 1 callback, at a random time somewhere in the middle.
I downgraded to firmware 6.90 and that fixed the issue (until the Connect app forced the upgrade again).
Web requests are still working on widgets.
Most of the discussion so far has been in this thread: https://forums.garmin.com/developer/connect-iq/f/discussion/207021/after-updating-fw-va3-to-7-00-makewebrequest-stopped-working