Sync file not saved after removing all source URLs from clippings

[aecreations]

Clippings 6.4b1+

If removing all source URLs from clippings from Clippings Manager, any synced clippings with their source URLs removed aren't immediately saved to the sync file. As a result, if the Synced Clippings folder is reloaded, the source URLs of the synced clippings will be incorrectly restored.

This appears to be a long-standing, unreported issue. Fix targeted for after 6.4b2+.