When creating the test to verify the upload progress notifications during client reset, it was discovered that the non-streaming upload notification callback was called one time with an estimate of 0.0 and then expired if there were no local or remote changes during the client reset. (The complete test log file is attached.)

Realm.Sync.Client.Session - Connection[1:66b04de3babb71ca336e205b] Session[4]: Progress handler called, downloaded = 0, downloadable = 0, estimate = 1.0000, uploaded = 0, uploadable = 0, estimate = 1.0000, snapshot version = 20, query_version = 0
Realm - Streaming Progress Progress callback called xferred: 0, xferrable: 0, estimate: 1
Realm - Non-Streaming Progress Progress callback called xferred: 0, xferrable: 0, estimate: 0

Since the non-streaming callback is being expired with this call and the streaming progress notification reports an estimate of 1.0, it seems to be more consistent to report an estimate 1.0 for non-streaming progress notifications in this case.