Problem description: in multiple places in frontend the items/problems that are rellated to child hostgroups are ignored when the parent hostgroup is selected in the corresponding filter fields or configuration parameters in multiple place in fronted:

1 - It is not possible to select parent hostgroup in the "Host group issues" screen element configuration window if this host group is empty.
2 - If a parent host group is selected in the "Group" field of the "Data overview" screen, then only the directly attached hots data is returned and hosts that belong to child groups are ignored. The same behavior is observed also for the "Host info", "Trigger info" and "Tigger overview" screens.
3 - Problems of Child hostgroups are not take into account when displaying the problems of the parent host group for in "Host group" map element in Monitoring => Maps
4 - Host groups filter field in Reports => Availability report does't take into account the items from child groups.

For details on how to reproduce these issues please check the subissues in ZBX-18595