How to save sub-object's thumbnails?

I have an object, let’s say UParent, which contains TArray<AActor*>, and those actors are sub-objects of UParent (Uparent object is their outer).
I noticed that every time some UParent object is loaded the engine will fire up the thumbnail render task and create a thumbnail for each of their Actor sub-objects.
But it seems that when the parent object is saved the thumbnails are not, so the editor recreates them every time.

Is there a way to save those thumbnails once and for all in the parent’s .uasset file? Or, as I don’t really need those thumbnails, disable their creation?