Core switch:
------------

interface config good:

interface Gi1/0/5
channel-group 7 mode active
switchport mode trunk
no lldp transmit
lldp transmit-tlv port-desc sys-name sys-desc sys-cap
lldp transmit-mgmt
no lldp med
exit

Interface config bad:

interface Gi1/0/22
channel-group 24 mode active
switchport mode trunk
no lldp transmit
lldp transmit-tlv port-desc sys-name sys-desc sys-cap
lldp transmit-mgmt
no lldp med
exit

Port channel 7 config:

interface port-channel 7
spanning-tree tcnguard
switchport mode trunk
exit

Port channel 24 config:

interface port-channel 24
spanning-tree tcnguard
no spanning-tree auto-portfast
switchport mode trunk
exit


Config Access switch 7 (core learns macs  from this one):
---------------------------------------------------------

interface GigabitEthernet1/1/1
 switchport mode trunk
 switchport nonegotiate
 channel-group 1 mode active
!

interface GigabitEthernet2/0/16 (a device is connected to this port)
!

interface Port-channel1 (link to core)
 switchport mode trunk
 switchport nonegotiate
!

Config Access switch 24 (core does not learn macs from this one):
-----------------------------------------------------------------
interface GigabitEthernet1/0/45
 description link to  csw_capa
 switchport mode trunk
 switchport nonegotiate
 channel-group 6 mode active

interface GigabitEthernet1/0/41 (a device is connected to this port)
!
interface GigabitEthernet2/0/45 (link to core switch)
 switchport mode trunk
 switchport nonegotiate
 channel-group 6 mode active

interface Port-channel6
 switchport mode trunk
 switchport nonegotiate
 spanning-tree link-type point-to-point


output show trunk on access switch 24:
Port        Mode             Encapsulation  Status        Native vlan
Po6         on               802.1q         trunking      1

Port        Vlans allowed on trunk
Po6         1-4094

Port        Vlans allowed and active in management domain
Po6         1,100-105,108-110

Port        Vlans in spanning tree forwarding state and not pruned
Po6         1,100-105,108-110