AhsayACB Continuous backup hangs with ProgramData folder as backup source

Continuous backup job for backup set with "ProgramData" folder selected as backup source is randomly hanging.

Further checking on the Continuous Backup Log (e.g. cdp.log) on the affected client computer, the following error message is displayed for the backup job that hang:

[YYYY/MM/DD hh:mm:ss] [erro] [CB.ErrorStream] com.ahsay.afc.bfs.cloud.d: [BackupSetIndex.updateBackupFile] sBackupJob=Current bf=[BackupFile][ClientPath=C:\ProgramData\Application Data\AhsayOBM\log\cdp.log.10][Type=F][BackupByJob=YYYY-MM-DD-hh-mm-ss][FileSystemObjectType=2]
...
[YYYY/MM/DD hh:mm:ss] [erro] [CB.ErrorStream] Caused by: com.ahsay.afc.db.bdb.f: [BlockDB.update] Cannot find key to update (Temp\backupset_id\OBS@backupset_id\index\index.b2b).