I haven't thought much about "Low share of voice" when I saw it first. I just decided to watch what happens.
I saw it whenever I was reducing my bids.
Just a minute ago, I saw it after I increased my bid:
A bid is 60 cents, and I decide to increase it for 5 cents, that is, to 65 cents. I do a bid change on an ad group level. There is one keyword only in that ad group with QS 10/10.
As I click on "Save", Low share of voice appears in the Status column.
As I go into the ad group, I see eligible besides the keyword. I go back to ad group level, it says eligible - low share of voice is gone.
So, I would say it is the way how system works, for whatever reason.
But why making people think over something that seems not to exist? Why triggering any stress with no reason?
Or, is there a reason for such system's behavior?