Can anyone suggest me If I apply rule for creating management zone which is host containing same Host_Group name . When I preview this I see all my server but when I save this rule and again I see in the preview at that time I only see few server in that management zone .Even my host_group name is same for all my server still it is happening. This is happening for all my application .
It's possible this may be happening due to the timeframe you have set. By default, the UI will use last 2 hours. If the hosts were not active in the time they will not display. Most previews use last 72 hours and will display anything detected during that time.
Double check the host properties and tag section for one of the hosts not showing in the management zone and ensure the host group is displayed there. If it does, opening a chat or ticket will be the best next step.