Magento 2 Cart Pricing Rule not getting applied when customer is already login and i am making change in rule from magento admin. In order to apply rule i have to logged out customer first, then login again. After this discount start getting applied. I am not sure about it. Magento version is 2.1.9 and it is in development mode.
This is normal behavior of the Sales Rule module. All discounts will be applied in case the totals have been recollected (as an example, when the shipping address was changed by the user). If you want to recollect all totals manually you should write a plugin for the saving new rule action, which gets all active quotes and manually recollects its totals, but this is not normal because it can take some time to obtain the result.