You created an App Rules (Firewall > App Rules or Firewall > App Control Advanced) to block the application according to the created Schedule interval (e.g. block application during lunch time). However, you find if user does not close the browser before the schedule block time, user can still access the application during the block time and if user close the browser and open again, the application will be blocked.
Is this the limitation of the browser or is there a work around on this issue?
This is the normal behavior. Sessions started before the schedule will maintain but no new sessions will be allowed as of the created policy.
To stop the current sessions which need to be killed, the logic needs to keep track of those sessions before any schedule policy takes effect. This would consume a lot more resources than system can afford as all potential sessions must be retained in a memory for this purpose.