Specifying the .Net solution to open in a dev container in Rider?

I set up a dev container for my .Net API I'm working on. It works well enough, except whenever I open the dev container, I get "Looking for solutions..." and it loops through my entire container looking for the .Net solution file.

The solution is in the root of my workspace, and is specified in the devcontainer.json. After loading the container and letting it search for several minutes, it does finally find the solution and open it.

Is there a way to specify the solution in the devcontainer.json file so I don't have to wait for it to search each time? I saw online somewhere that the customizations > jetbrains > settings > SolutionFile should let me specifiy this, but it doesn't seem to be working.

Is this because I'm using the newer .slnx solution format instead of the older .sln? Or do I just have the setting wrong?

{
    "customizations": {
        "jetbrains": {
            "backend": "Rider",
            "plugins": [],
            "settings": {
                "Git4Idea:app:Git-Application-Settings.staging_area_enabled": true,
                "com.intellij:app:BuiltInServerOptions.builtInServerPort": 52108,
                "com.intellij:app:HttpConfigurable.use_proxy_pac": true,

                "SolutionFile": "/workspace/MyProject.slnx",

                "BackendType": "Local",
                "EnableDotNetCoreCLR": true,
                "RunConfigurationsEnabled": true,
                "AutoOpenSolution": true
            }
        }
    },
    "containerEnv": {
        "NUGET_PACKAGES": "/home/vscode/.nuget/packages",
        "DOTNET_CLI_HOME": "/home/vscode",
        "DOTNET_SKIP_FIRST_TIME_EXPERIENCE": "1",
        "DOTNET_USE_POLLING_FILE_WATCHER": "false",
        "CHOKIDAR_USEPOLLING": "false",
        "WATCHMAN_DISABLE_RECRAWL": "true"
    },
    "dockerComposeFile": "docker-compose.yml",
    "features": {
        "ghcr.io/devcontainers/features/dotnet:2": {
            "version": "9.0",
            "installUsingApt": true
        },
        "ghcr.io/devcontainers/features/node:1": {
            "version": "lts",
            "nodeGypDependencies": true
        },
        "ghcr.io/devcontainers/features/git:1": {
            "version": "latest"
        }
    },
    "forwardPorts": [
        5432,
        7071,
        5173,
        15888
    ],
    "mounts": [
        "source=myproject-nuget-cache,target=/home/vscode/.nuget/packages,type=volume",
        "source=myproject-dotnet-tools,target=/home/vscode/.dotnet/tools,type=volume",
        "source=/var/run/docker.sock,target=/var/run/docker.sock,type=bind",
        "source=myproject-rider-config,target=/home/vscode/.config/JetBrains,type=volume",
        "source=myproject-rider-plugins,target=/home/vscode/.local/share/JetBrains,type=volume"
    ],
    "name": "MyProject Development",
    "overrideCommand": false,
    "portsAttributes": {
        "5432": {
            "label": "PostgreSQL",
            "onAutoForward": "notify"
        },
        "7071": {
            "label": "API",
            "onAutoForward": "openBrowser"
        },
        "5173": {
            "label": "Web Client",
            "onAutoForward": "openBrowser"
        },
        "15888": {
            "label": "Aspire Dashboard",
            "onAutoForward": "openBrowser"
        }
    },
    "postCreateCommand": "bash .devcontainer/post-create.sh",
    "postStartCommand": "echo 'Container ready! Solution: /workspace/MyProject.slnx'",
    "remoteUser": "vscode",
    "runArgs": [
        "--init"
    ],
    "service": "devcontainer",
    "workspaceFolder": "/workspace",
    "workspaceMount": "source=${localWorkspaceFolder},target=/workspace,type=bind,consistency=cached"
}