Hello Greg,

probably there is a problem on the forwarding plane

verify with

sh mpls ldp discovery

if you see correct LDP adjacencies on all MPLS interfaces of core router.

if you don't see the neighbor LDP router-id followed by :0 that link is not working well.

and verify with

sh mpls forwarding PE-loopback-address correct action should a label value or pop tag if you see untagged this breaks the MPLS VPN connectivity.

in that case do shut wait 60 seconds no shut of the link to give LDP a chance to restart on the link

Hope to help

Giuseppe