Failover: ext managed dns failing to detect WAN status

Balance 305
WAN1, Drop-in mode for primary ISP
WAN2, NAT mode for backup ISP, always on, outbound HTTP allowed, four (4) hosts nat’d
External managed DNS failover with

DNSmadeeasy correctly detects primary IP’s as DOWN when WAN1 is offline. However, it also detects the failover IP’s as DOWN. So, no external DNS failover occurs.

Am I missing something in the Balance 305, to respond to the DNSmadeeasy monitors?
The monitors for four (4) hosts are as follows:
ftp: monitor protocol TCP port 21
webserver: monitor protocol HTTP port 80
vpn: monitor protocol HTTPS port 443
mail: monitor protocol HTTPS port 443

I also have a support ticket into DNSmadeeasy.

UPDATE: User error. Resolved.