So seems the L2L VPN connection is up but no traffic is flowing?
I would presume that in that case the L2L VPN connection is probably negotiated from the side of Azure.
You might be missing NAT0 configuration for the subnets/addresses configured on the L2L VPN connection. This would explain atleast why connection could be up (negotiated from remote site) but no traffic was flowing (not having proper nat configuration would make it so that traffic from your side would not match the VPN configurations)
Naturally we could take a look at the PIX configurations.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...