cant preview time effect in material

hi

i have a material with an input dependent on a calculation that uses time
i want to preview the material in the material editor
but i am unable to see the material change in the material editor in the preview screen
the only way i can view the material effect is to apply the material to a mesh etc and view that in its blueprint
the culprit seems to be time - the time input does not change in the material blueprint so that everything else in the material blueprint dependent on time do not change
i was under the impression that time will increment in the material editor - a lot of material examples seem to get it to

thanks