Cisco STP Issue

Hello, I am working on an issue for someone that has me stumped. There are two locations with this network. The second location is connected via trunk. The core is at the the main location and all vlans for the second location live there. They have a problem where they lose connectivity intermittently. And it is because of spanning-tree topology changes as far as I can tell. All switches are in rapid-pvst mode. The priority on all vlans is set from 4096 on the core and the priority on all switches at the second location are set to 61440. Yet at this location the root bridge keeps changing despite the priority and then wireless clients lose connectivity for the 45 sec network convergence takes. Every 15-45 min the root bridge changes to one of the switches local to this location then 5 min later back to the core at the other location. I can't see why this continues to happen even after setting the lowest possible priority on all switches at the second location. Any direction anyone could offer would be greatly appreciated.

This is the spanning-tree config on all devices at the second location.

spanning-tree mode rapid-pvst spanning-tree loopguard default spanning-tree logging spanning-tree portfast bpduguard default spanning-tree extend system-id spanning-tree backbonefast spanning-tree vlan 10,12,20,50,60,80,100,102,150,170-171,192-193 priority 61440 spanning-tree vlan 200,300-303 priority 61440 

This is the spanning-tree config on the core .

spanning-tree mode rapid-pvst spanning-tree loopguard default spanning-tree logging spanning-tree portfast bpduguard default spanning-tree extend system-id spanning-tree backbonefast spanning-tree vlan 10,12,20,30,50,60,80,100,102-103,150,170-171 priority 4096 spanning-tree vlan 192-193,200,300-303 priority 4096 

Here are some of the traps from the core. (Note, the mac ending in e580 IS the core and gi1/0/48 is the port facing the second location.)

Sep 19 10:11:40.598 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 300: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 00af.1fc6.e580 Sep 19 10:12:47.707 CDT: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/48 on VLAN0301. Sep 19 10:12:47.727 CDT: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 301 Sep 19 10:12:47.727 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 301: New Root Port is GigabitEthernet1/0/28. New Root Mac Address is 381c.1a39.c800 Sep 19 10:12:48.718 CDT: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/48 on VLAN0303. Sep 19 10:12:48.729 CDT: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 303 Sep 19 10:12:48.729 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 303: New Root Port is GigabitEthernet1/0/28. New Root Mac Address is 381c.1a39.c800 Sep 19 10:13:33.705 CDT: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet1/0/48 on VLAN0010. Sep 19 10:13:33.705 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 00af.1fc6.e580 

Here are log messages form the user switch where connectivity is being lost.

Sep 19 10:11:40.588 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 300: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 00af.1fc6.e580 Sep 19 10:12:47.711 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 301: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 381c.1a5f.7800 Sep 19 10:12:48.718 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 302: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 381c.1a5f.7800 Sep 19 10:13:33.942 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 00af.1fc6.e580 Sep 19 10:16:31.553 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 303: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 381c.1a5f.7800 Sep 19 10:16:32.622 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 301: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 381c.1a5f.7800 Sep 19 10:16:41.598 CDT: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/24. New Root Mac Address is 00af.1fc6.e580 

You can find a crude drawing of the setup here..... https://imgur.com/xv6HFsT

What it looks like to me is that the switch with a mac ending in c800, despite having a lower priority, keeps becoming the root bridge and forcing the main switch for the location to block the vlan on the trunk connecting to the core. I do not understand why this would be happening.