Host group elements filtered by tag not working

Given I have following hosts in "Virtual machines" group:

• v1.s1 tagged with "hypervisor: s1"
• v2.s1 tagged with "hypervisor: s1"
• v1.s2 tagged with "hypervisor: s2"
• v2.s2 tagged with "hypervisor: s2"

When I want to create a map element with type "Host group", show as "Host group elements" (to show all individual hosts) with "Host group" set to "Virtual machines" and "Tags" set to hypervisor Equals s1, all hosts from "Virtual machines" group are rendered. 

I'd expect only hosts from "Virtual machines" group tagged with "hypervisor: s1" to be displayed.