This problem can occur if you have configured the WLAN to operate in bridged mode, but have created an SVI for the VLAN on the AP, there is no mechanism to prevent this unsupported configuration for occurring.
From Best Practices :
Switched Virtual Interface
When a Wireless Controller or Access Point bridges traffic on a VLAN it does not require a Switched Virtual Interface to be defined. One common mistake is to create a Virtual Interface for locally bridged VLANs on a device when it’s not required. A Virtual Interface is only required for the following scenarios:
1. Layer 3 Access Point adoption.
2. Device Management.
3. When the Wireless Controller or Access Point is providing IPv4 routing services between multiple IPv4 interfaces.
4. When the Wireless Controller or Access Point is providing NAT.
5. When the Wireless Controller or Access Point is terminating IPsec VPN tunnels.
6. When DHCP services are running on the Wireless Controller or Access Point.
Please note that all routed IPv4 traffic is inspected by the stateful packet inspection firewall. When IPv4 routing doesn’t work as expected with the defined Virtual IP interfaces, issue a service pktcap on drop command to see if any packets are being dropped by the stateful packet inspection firewall. Most firewall checks are enabled by default and can be disabled if needed.
