Can you please check is there any mac moves? or port is going into down or port going into an error-disabled state?I have observed the same behavior in my environment. I found there were mac moves happening which was resulting in port go into an erro...

I believe the APIC controller doesn't hold the authority of control plan traffic in ACI, control plane+data Plane is handled by all the leaf/spine switches. MGMT plane holds by the APCI controller if I am not mistaken here. I may be wrong so an exper...