Why did it take eight months for Stuff to apologise?

Stuff reports:

On 5 August 2018, the Sunday Star Times published a story which made a number of incorrect statements about Hon. Tim Groser, and in particular about his decision not to seek an extension to his term as NZ’s Ambassador to the United States. These statements were repeated on the Stuff website.
Stuff accepts those statements were incorrect and unreservedly apologises to Mr Groser for those errors.
Mr Groser, a former Trade Minister, trade negotiator and diplomat, recently returned to NZ after successfully completing a term as Ambassador to Washington. The decision not to seek an extension to his term was made entirely by Mr Groser. 

What I find fascinating it it took almost nine months for Stuff to retract their story and apologise. Why did it take so long?