Here is a report on AM and their express carrier-Aerolitoral.

I had ZED tickets on AM for PVR-GDL and then GDL-CUL.
At PVR, they told me that they cannot accept my ticket because it is Aerolitoral on an AM flight number and that I would have to buy a ticket for $80, which I did do. They said I would have to buy a GDL-CUL ticket for $200 also.
Anyway,
In GDL, it was the same situation, only they had no problem accepting my zed ticket and off I went to CUL without any issues.

I think I will avoid using AM in the future unless absolutely necessary.