Wikipedia says
The stay in Britain was troubled, however, including running aground at Spithead on 19 June, forcing her to be drydocked for repairs, brawls with locals and a near-mutiny resulting from the unfamiliarity of the Greek sailors with blue cheese
And a bit of googling gives other mentions, but no explanation. https://en.m.wikipedia.org/wiki/Greek_cruiser_Georgios_Averof
The passage in Wikipedia is lifted directly from this book which seems to be a passion project and doesn't offer further citations.
You can find unsourced statements to the effect of "[the ship's] first voyage, to Britain for the coronation of King George V, was marred by a brawl between sailors and locals. They had been served blue cheese, something the sailors had never seen before. They thought it was moldy and took it as an insult." which might be provide some context.
But, it should also be kept in mind that, per Fotakis' Greek Naval Strategy and Policy 1910-1919 those brawls and "near mutiny" should be seen in the context of a severe general discontent among the sailors bred out of harsh treatment by the ship's officers.