No crypto debugs appear when trying to initiate the tunnel. IPSec worked before adding generic routing encapsulation (GRE) to the configuration.
To add GRE to a working IPSec configuration, follow these steps.
int tunnelip address private_ip subnet_masktunnel source outside_interface_nametunnel destination peer_address
ip address private_ip subnet_mask
tunnel source outside_interface_name
tunnel destination peer_address
access-list acl_name permit gre host tunnel_source_ip host peer_address
For more information, including a sample configuration, see Configuring Router-to-Router IPSec (Pre-shared Keys) on GRE Tunnel with CBAC and NAT.