Log file contains the following:

Caught exception evaluating: it.availableBackups in /jenkins/thinBackup/restoreOptions. Reason: java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
<details omitted for clarity>
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.substring(String.java:1911)
at org.jvnet.hudson.plugins.thinbackup.backup.BackupSet.initializeFromZipFile(BackupSet.java:129)
at org.jvnet.hudson.plugins.thinbackup.backup.BackupSet.initialize(BackupSet.java:93)
at org.jvnet.hudson.plugins.thinbackup.backup.BackupSet.<init>(BackupSet.java:79)
at org.jvnet.hudson.plugins.thinbackup.utils.Utils.getValidBackupSetsFromZips(Utils.java:352)
at org.jvnet.hudson.plugins.thinbackup.utils.Utils.getValidBackupSets(Utils.java:371)
at org.jvnet.hudson.plugins.thinbackup.utils.Utils.getBackupsAsDates(Utils.java:284)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupMgmtLink.getAvailableBackups(ThinBackupMgmtLink.java:159)
... 129 more

Looking at source I see

tmpName = tmpName.substring(0, tmpName.indexOf(File.separator));

I suspect File.separator is the Windows character, but the version used to save the archive is the Linux version.