By Nicola Fahey THE BBC axed celebrity adventure series Trailblazers after two of its main stars fell out during filming. Mel B and Emily Atack clashed during the first series, on a trek across the Rocky Mountains with Ruby Wax. The 2022 show saw the stars follow in the footsteps of female Victorian explorer Isabella Bird. But a source claims Mel, 43, and 34-year-old Emily didn’t get on – and the atmosphere in the US became “frosty” and “quite tense” after an argument halfway through filming. The insider said: “Once on set, their personalities definitely clashed and there was one row that was …