TypeError: Argument 1 passed to _auditfiles_used_not_referenced_batch_display_get_files() must be of the type array, string given

On our sites, clicking "Reset file list" followed by "Load all files" results in the following fatal error during batch processing:

An AJAX HTTP error occurred. HTTP Result Code: 500 Debugging information follows. Path: /batch?id=569&op=do StatusText: error ResponseText: TypeError: Argument 1 passed to _auditfiles_used_not_referenced_batch_display_get_files() must be of the type array, string given, called in /code/includes/batch.inc on line 284 in _auditfiles_used_not_referenced_batch_display_get_files() (line 289 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

This is followed by the following PHP notices on the subsequent report page:

Warning: Illegal string offset 'field_audio_block_files' in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Notice: Array to string conversion in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Warning: Illegal string offset 'field_article_media' in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Notice: Array to string conversion in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Warning: Illegal string offset 'field_tag_photo' in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Notice: Array to string conversion in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Warning: Illegal string offset 'field_media_file' in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Notice: Array to string conversion in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Warning: Illegal string offset 'field_event_image' in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

Notice: Array to string conversion in _auditfiles_used_not_referenced_batch_display_get_operations() (line 264 of /code/sites/all/modules/auditfiles/auditfiles.usednotreferenced.inc).

For context:

• field_audio_block_files, field_article_media, and field_media_file are core "File" fields.
• field_tag_photo and field_event_image are core "Image" fields.