Bridge Mode on MG7550

I have been attempting to put my Motorola MG7550 into bridge mode using the instructions on Motorola's "How Do I Put My Cable Modem + Router Combo (also called a Gateway) into Bridge Mode, So I Can Connect Another Router behind It?" article.  While it appears that it completes the configuration successfully, the router (Mikrotik hAP ac2) I have plugged into Port 1 on the MG7550 and ether1 on the hAP is never handed an IP from Comcast.  To troubleshoot I put a hub between the two units to sniff the traffic and I can see the hAP asking for an IP but nothing is ever returned. 

Is there something further that needs to be done on either the hAP or in concert with Comcast support to get the IP address issued? 

I have tried changing the MAC of ether1 on the hAP to both the inside and outside MAC address of the MG7550 to see if that would make a difference and it hasn't changed the outcome.  

I do have an older Arris SBG6580 I could swap in, but I wanted to hold off doing that until I exhausted my options with the current configuration.

 Appreciate any help or insight into the issue.

Thanks