iOS 11.4 only request .well-known/… | Apple Developer Forums

My app's associated domain does't work ant iOS 11.4 and iOS 12 beta. After some research I found that after iOS 11.4 only request

/.well-known/apple-app-site-association

when server response with 301 redirect to error.html。

"GET /.well-known/apple-app-site-association HTTP/1.1" 301 194 "-" "swcd (unknown version) CFNetwork/948.2.1 Darwin/18.0.0" 
"GET /.well-known/apple-app-site-association HTTP/1.1" 301 194 "-" "swcd (unknown version) CFNetwork/948.2.1 Darwin/18.0.0"

Before iOS 11.4, iOS will request

/apple-app-site-association

when

/.well-known/apple-app-site-association

failed, and log is like this:

"GET /.well-known/apple-app-site-association HTTP/1.1" 301 194 "-" "swcd (unknown version) CFNetwork/948.2.1 Darwin/18.0.0" 
"GET /apple-app-site-association HTTP/1.1" 200 466 "-" "swcd (unknown version) CFNetwork/948.2.1 Darwin/18.0.0"

Does anyone know is this a bug on iOS 11.4 or a new restrict about 301 redirect?

iOS 11.4 only request .well-known/apple-app-site-association