WHS how long can a counting score count?

Ive got this exact thing happening to me, my 20th score not counting or effecting my handicap despite it being the 3rd best differential. It affects my playing handicap too!
 
A mate of mine has a counting round from 1st Sept 2018. It's the 20th round on his list. So there's no 3 year cut off.
I think the 3 years was purely for the creation of new HI's under WHS.
 
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