In January, World Boxing extended the rules to include male boxers.
World Boxing introduced mandatory genetic sex testing last year for female competitors aged 18 and above. It said the tests were to ensure"the safety of all participants and provide a level playing field", with national federations responsible for ensuring samples were processed.
The decision also cost him the chance to try to qualify for the Olympics. Francis said he is planning to turn professional.
"They got me in a room and told me that I couldn't box because they didn't know if I was a boy or a girl, basically,"Francis told BBC Sport.
He said the explanation was that they could not provide a blood sample for him in time."They were speaking to me and I couldn't even really hear,"he said.
"I can't put into words how it just doesn't make sense,"Francis said.
The federation said George remained a valued member of the England team, including representing the squad as flag bearer.