While using low level discovery I used
ifInOctets["index","ifDescr","

{#SNMPVALUE}"]
for the OID and
ifInOctets["{#SNMPVALUE}

"]
for both the key and name.

This generates an item like this:

ifInOctets["index", "ifDescr", "1/2/7, 10/100/Gig Ethernet SFP, "to 7705-1.lnbg GE1/1/7 PathC via CRMT""]

However it's not a valid item because the " isn't escaped so zabbix marks the item as Not_supported. It should generate:

ifInOctets["1/2/7, 10/100/Gig Ethernet SFP, \"to 7705-1.lnbg GE1/1/7 PathC via CRMT\""]

I marked this as major because it totally breaks the ability to use lld on many of our routers.

Let me know if you need more information.