We recently deployed VRF groups on our core switches and there are a few key changes to troubleshooting/configuration.
Standard way: ping 192.168.1.1
w/ VRFs: ping vrf NAME 192.168.1.1 (where NAME is the name of the vrf group)
Standard way: traceroute 192.168.1.1
w/ VRFs: traceroute 192.168.1.1 /vrf NAME
If you are trying to make a connection to a destination that resides in a VRF from the core switches you will most likely have to include some sort of VRF tagging. This even applies to services like RADIUS, NTP, DHCP Relay, and TACACS.