Confirmed uplink not automatically retransmitted

My understanding is that if a confirmed uplink is not ACK'ed, the module firmware is supposed to automatically retransmits the frame. The number of retries is set by the mcpsReq.Req.Confirmed.NbTrials variable which is 8. After 8 attempts, it will give up and leave it up to the application to deal with it.

The problem I am having is that I have not been able to observe the MKRWAN automatically retransmit a confirmed uplink if the uplink ACK is not received. Or, if it is being received, the firmware behaves as if it isn't. I have confirmed that the server got the uplink and the server does say it sent an ACK. But occasionally the module doesn't appear to receive the ACK.

Can anyone else confirm they have observed the module automatically retransmit a confirmed packet when it doesn't receive an ACK?