It works as designed by Mitel. Unfortunately Call history is only available for the calls routed to the phone's prime line.
From the "Call History" help (e.g. 5312, 5324 phones) and from the "Call History Application" (5320/5320e, 5330/5330e, 5340/5340e, 5360), 5560 IPT phones) help:
"A call is only logged at the phone whose prime line is called. For example, if a phone with prime line 2000 answers an incoming call to multicall extension 2001, the call is only logged at the phone whose prime line is 2001."