WinDRBD – Why Does WinDRBD Become Diskless/StandAlone?

I have a question.

Currently, this OS is Windows Server 2019.
The volume configuration is Raid-5.
The two servers are connected by a heartbeat network
Both nodes were mirrored using WinDRBD. Both nodes have the same configuration.
I left unformatted G: and set D: to be visible to the primary node.

my resource are below

include "global_common.conf";

resource "foo" {
    protocol    A;

    net {
        use-rle no;
    }
    on node1 {
        address     XXX.XXX.XXX.XXX:7600;
        node-id 1;
        volume 1 {
            disk        "G:";
            device      minor 1;
            meta-disk   internal;
        }
    }
    on node2 {
        address     XXX.XXX.XXX.XXX:7600;
        node-id 2;
        volume 1 {
            disk            "G:";
            device      minor 1;
            meta-disk   internal;
        }
    }
}

Both nodes worked normally.
The tests were completed by switching roles.
( primary → secondary / secondary → primary )

However, the problem occurred after booting.

After booting, the status appears as below. (both nodes)

foo role:Secondary
  volume:1 disk:Diskless
  node2 connection:StandAlone

I thought and searched a lot, but couldn't find an answer.

There were a few things I was suspicious about.

I wonder if it's because I tried before the G: letter was assigned to the drive.
If my thinking is correct, is there a workaround?

If it is now my opinion, but the above problem continues to occur, what is the cause?

Once it was solved in the following way.
But I want to find the cause and fix it accurately.

drbdadm down foo
drbdadm up foo

Thanks in advance for your help.