Nonstop Backup Recovery Not Restoring All Files

I have a nonstop backup setup that backups a folder located on an internal hard drive to an external hard drive connected via USB. Though I've had success recovering from this backup in the past, for about the past two weeks when I try to recover from it only some of the contents of the folder are restored. I've checked the contents of the backup by right-clicking the folder whose contents I'd like to restore and clicking 'Acronis Recovery' followed by 'Open' after selecting the backup version I'm interested in. Everything seems to be there, but when I try to copy from the backup or perform a recovery only a portion of the folder's contents are restored. Once the recovery process is initiated, the Acronis taskbar icon pops up and displays until about 25% of the process is completed, then it disappears. I've checked the log but could find nothing pertaining to the nonstop backup.

Does anyone have an idea what might be going on? Thanks in advance for any help you can provide.