How to use hook_block_view_MODULE_DELTA_alter on Views-exposed form?
I think this is an issue with block module and may be you get your answer here. Please check the url

https://www.drupal.org/node/1076132
https://api.drupal.org/api/drupal/modules!block!block.api.php/function/hook_block_view_MODULE_DELTA_alter/7