how to catch grpc protocol?

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Hi, My wireshark Version 3.2.2 (v3.2.2-0-ga3efece3d640) and I can catch protocol http2 (really is grpc) .but I type grpc is empty. but sometimes is successful！！！

if you start wireshark first and start your gprc server you can catch grpc,but if you start your grpc server first and start wireshark , you can catch only http2 .(no grpc)

http2

grpc