Can not join when session is created on Play-In-Editor

I made a simple network test program which can do CreateSession and FindSession-JoinSession.

I used C++ template for further development, but until now just used Blueprint script only.

Here is my problem.

When I run host as standalone, I can join to that session.

But when I run host as Play-In-Editor, I can not join to that session.

Log of client says “Can’t start an online session (Game) in state InProgress”

So I printed Match State for debugging on host, then found state is Sever:InProgress on PIE and InProgress on standalone.

Why this difference happens? and How can I fix this?