Magento – Catalog price rule doesn’t apply if the date is set to today

Problem in this instance is on these lines

$fromTime = (int) strtotime($rule->getFromDate());
$toTime = (int) strtotime($rule->getToDate());

They are not using Magento time methods to take in to consideration timing zones and in the comparison it uses following line. (Few lines after the above lines)

$coreDate  = $this->_factory->getModel('core/date');
$timestamp = $coreDate->gmtTimestamp('Today');

If you update the first two lines to

$fromTime = (int) Mage::getModel('core/date')->gmtTimestamp(strtotime($rule->getFromDate()));
$toTime = (int) Mage::getModel('core/date')->gmtTimestamp(strtotime($rule->getToDate()));

Note that now both uses gmtTimestamp which is inline with the comparison. This should work fine. Obviously add a class override.

1)Create an attribute and using "Update attributes" option select all those products to one attribute value and apply catalog price rule to that attribute. This is not answer to your first point. but it is the other way for applying rules for the products.

2)check cron job is working or not . If not working, than catalog price rules will disappear after some time. click on "Apply catalog price rules" again when it disappear and reindex .

3)Dont select date when creating catalog price rules. leave the "from and to date" to blank. Check even your server time and magento site time is same.