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Page Impressions are fine for me though.
Why does Google will update impressions promptly but sometimes (quite often actually) delay clicks?
Page Impressions = No cost to Google nor advertiser
Clicks = Cost to Advertiser and Google
Maybe they're performing manual checks, who knows, they certainly do not tell us?
My Click stats are very slow today unlike yesterday, Sunday, when they seem to be automated and regular with the Page Impressions increase.
Possibly they are testing new anti-fraud ideas and we'll know nothing about them in the short-term, possibly never.