Backup and restore

Hi, 

we have problem with backup and restore SCORM module,

in .mbz file: files.xml

<files>

  <file id="4013">

    <contenthash></contenthash>

    <contextid>377</contextid>

    <component>mod_scorm</component>

    <filearea>content</filearea>

    <itemid>0</itemid>

    <filepath>/res/</filepath>

    <filename>index.html</filename>

 <contenthash></contenthash> - tag is empty for every one file

Hoe can i fix that?