Summary
The following error is seen for one or more SNMP Channels "- Error - Error building ASN.1 representation" on a GPX-PRO (32 or 8).
Cause
The SNMP Device doesn't support SNMPv2 or the OID being used doesn't conform to to the SNMP v2 RFC3416
Solution
Setting the SNMP version to 1 instead of 2 for all the should resolve the issue.