SNMP access via VRF interface -
I know this is an old thread, however was having same issue and was looking for a solution and happened on this thread.
I was able to eventually resolve issue, so wanted to add solution so may assist others with same issue.
device: cisco ASR1001-X
IOS: Gibraltar - Version 16.12.4
regular command (I am using snmpv3)
snmp-server host 10.x.x.x version 3 priv <username>
for vrf
snmp-server host 10.x.x.x vrf <vrf-name> version 3 priv <username>
I assume similar for v2.