Date filter loses selection values

@graouxx, please try the following workaround to make sure we're talking about the same problem.
In date/includes/date_api_filter_handler.inc, please find function init() and modify the following segment:

    if (empty($this->options['exposed']) || (isset($this->options['expose']['identifier']) && !isset($_GET[$this->options['expose']['identifier']]))) {
      $this->force_value = TRUE;
    }

to

    if (empty($this->options['exposed']) || (isset($this->options['expose']['identifier']) && !isset($_GET[$this->options['expose']['identifier']]))) {
      $this->force_value = FALSE;
    }

i.e., just keep force_value to FALSE.

Does this solve the problem?

According to my tests, Date 6.x-2.2 fixes this problem. So marking as fixed unless I hear back from the poster.

Can you please explain the symptoms in detail:
* Do the initial filter settings cause empty results? If so, then VBO will fail; it's a known issue: #487372: VBO breaks if views returns empty results with default values for exposed filters
* Is the selection lost at the confirmation screen when "Select across pages" button is clicked? If so, then it's a resolved issue with the latest dev release: #522418: More rows exported than selected during the execution of the operation when using a Date filter
* Is the selection lost even if "Select across pages" button is not clicked? If so, then this works on my side. You will need to give details about the date filter settings. Also, does VBO work correctly for you *without* a date filter?

OK then, please subscribe to the other issue.