Sir Ronald Syme states only one legion was lost. (Journal of Roman Studies, Vol. 18 (1928), pp. 41-55)
Brian Jones also agrees to one legion was lost. (Suetonius: The Flavian Emperors, p.135)
Pat Southern in her bio of Domitian says one standard was lost by Fuscus (possibly a Praetorian standard and not a legionary eagle), however she also agrees with Jones that it cannot be that of the V Alaudae because that legion was lost long before the Dacian campaign. Jones states the legion did not survive 69/70 AD. (Southern - Domitian: Tragic Tyrant, p. 98 and Jones - The Emperor Domitian, pp. 138-143)