I came across this post in trying to find a solution for what seems to be the same issue.
Test email sends fine, scheduled job doesn’t send anything.
Duplicacy Personal 2.1.0 on Windows running as administrator with service enabled.
Verbose logs have nothing:
10:00:37.244 Saved file snapshots/###########/7 to the snapshot cache
10:00:37.315 Uploaded file snapshots/###########/7
10:00:37.315 Backup for C:\Users\########### at revision 7 completed
10:00:37.315 Files: 62792 total, 38,296M bytes; 87 new, 215,424K bytes
10:00:37.315 File chunks: 7722 total, 38,688M bytes; 16 new, 99,574K bytes, 26,373K bytes uploaded
10:00:37.315 Metadata chunks: 7 total, 21,082K bytes; 7 new, 21,082K bytes, 7,157K bytes uploaded
10:00:37.315 All chunks: 7729 total, 38,708M bytes; 23 new, 120,656K bytes, 33,530K bytes uploaded
10:00:37.315 Total running time: 00:00:35
10:00:37.315 12 files were not included due to access errors
10:00:37.315 Deleting the shadow copy used for this backup
10:00:37.407 The shadow copy has been successfully deleted