This could be related to ZBX-21515{}

Steps to reproduce:

1. Create custom tag: class:raid
2. Assign to a template.
3. In "Latest Data", list the group in which has a host that includes the template with above tag.
4. Select the filter: class: raid
5. Observe that the filter filters out everything except data represented by selected template.
6. In "Latest Data", list a group that has no hosts of above template.
7. Observe no data is listed.

Applying the  Reset button clears everything including the selected group.  Without resetting, tags cannot be deselected that do not apply to the currently filtered group.