Vertically centers the selected objects. If only one object is selected in Draw or Impress, the center of the object is aligned to the vertical center of the page.
Open context menu - choose Alignment - Centered (objects selected) (Collabora Office Impress, Collabora Office Draw).
On Align bar (Collabora Office Impress, Collabora Office Draw), click
Centered
To align the individual objects in a group, choose Format - Group - Enter Groupdouble-click to enter the group, select the objects, right-click, and then choose an alignment option.