Resolution:
According to our documentation:

Since an action is performed only after results from a test evaluation are received (even if the consequence is deferred), an action might not be performed immediately after a test condition becomes true. The delay can be as large as the data source collection interval plus any escalation period. For example, if an action has an escalation period of five minutes but the test is only evaluated every two minutes, it may be from five to seven minutes before the action is performed.
So if you have a rulebase with poll interval 2 minutes and escalation period of 5 minutes, the action will be triggered 5 to 7 minutes after the first true evaluation time. This is based on that the true condition is never changed. If the poll interval is 2 minutes and escalation period is 1 minute, the action will be triggered after 2 minutes which is the next evaluation time.

When will the action get triggered if I am using a escalation period for the action?