PDO Exception with Empty (Sub) Fields - Incorrect Decimal Format

I am not able to submit blank values for any MVF fields (that are optional). Even with the default value empty, and the default unit set to "-None-", if I do not enter a value for any MVF optional field, I get this error:

PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect decimal value: '' for column 'field_annual_production_value' at row 1: INSERT INTO {field_data_field_annual_production} (entity_type, entity_id, revision_id, bundle, delta, language, field_annual_production_value, field_annual_production_target_id) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7); Array ( [:db_insert_placeholder_0] => node [:db_insert_placeholder_1] => 3676 [:db_insert_placeholder_2] => 3788 [:db_insert_placeholder_3] => project [:db_insert_placeholder_4] => 0 [:db_insert_placeholder_5] => und [:db_insert_placeholder_6] => [:db_insert_placeholder_7] => _none ) in field_sql_storage_field_storage_write() (line 494 of /home/nexampweb/dev/modules/field/modules/field_sql_storage/field_sql_storage.module).

I read here (http://drupal.stackexchange.com/questions/16051/pdoexception-incorrect-d...) that is has to do with a decimal type field attempting to be saved as NULL or a blank string ''. I also found there is some kind of logic that tries to account for empty values in this modules code, but it doesn't seem to attack the NULL issue:

(mvf.module:976)

/**
 * Implements hook_field_is_empty().
 */
function mvf_field_is_empty($item, $field) {
  // The logic is the following. Normally if at least one sub field is empty,
  // the entire field is considered empty. However, if it is value for default
  // value of MVF, we consider it empty only if all the sub fields are empty.

The solution on that linked article does not seem to help with this instance, however. Is there any way to fix this or workaround it without requiring the user to enter a value?