Error message on Synchronize database to filesystem / Update search index

warning: array_shift() [function.array-shift]: The argument should be an array in ... batch.php on line 558

While the module is reading the genre info from the ID3 tags, it is drawing blanks on the genre search which I highly suspect is related to this error message - i.e. if you click, for example, 'Blues', it says 0 results even though it read the blues tag from the album itself and also lists the blues taxonomy if you go directly to the album view.

I have tried installing the development version but there is no change.