Hash / Array - Formatting Issue with ConvertTo-Json

Question

I'm taking a list of users, and then using the following code to loop through them and build a chunk needed for a json request in a specific format.

$teamMembers = @();
foreach ($item in $userIds) {
    $team = @{
        id = $item
        type = 'User'
        roleTypes = @(
            'TeamContributor'
        )
    }
    $teamMembers += $team
}

After this hash list is created, I then need to append it to a string as follows to create a JSON string.

$body=@{name=$name;teamMembers=$teamMembers} | ConvertTo-Json -Compress

The issue i'm having is that when I run the ConvertTo-Json, it's ignoring my roleTypes array and treating it as a string.

If I run the ConvertTo-Json command on just the $teamMembers variable it looks file, but when I combine it to build the body variable that's where it goes wrong.

Here is the example of the desired format of this output:

{
    "name": "Name Here",
    "teamMembers": [
        {
            "roleTypes": [ "TeamContributor" ],
            "id": "ID Here",
            "type": "User"
        },
        {
            "roleTypes": [ "TeamContributor" ],
            "id": "ID Here",
            "type": "User"
        },
    ]
}

Here is what i'm getting instead:

{
    "name": "Name Here",
    "teamMembers": [
        {
            "roleTypes": "TeamContributor " ,
            "id": "ID Here",
            "type": "User"
        },
        {
            "roleTypes": "TeamContributor " ,
            "id": "ID Here",
            "type": "User"
        },
    ]
}

Any suggestions on the best way to accomplish this? Thank you in advance for any assistance!