Suave @Ana Leticia Sampaio?
Tenta fazer com uma ALLEXCEPT. Ficaria assim:
VAR _LastDate =
CALCULATE(
MAX(fContas[Account Phase Date From]),
ALLEXCEPT(fContas, fContas[Account_id], fContas[Account Phase Context])
)
RETURN
CALCULATE(
MAX(fContas[Account Phase]),
FILTER(
ALLEXCEPT(fContas, fContas[Account_id], fContas[Account Phase Context]),
fContas[Account Phase Date From] = _LastDate
)
)
Abs!