Why won't this function work with a piped variable?

I created this function that parses a field for specific text and returns a custom object.

Everything works fine if I use the syntax, Get-MachineUser -VMArray $PassedArray but it doesn't work if I pipe the array $PassedArray | Get-MachinesUser.

I worked with someone on my team and we figured out when we pass the array it is only processing the last entry in the array. I don't mind using the other syntax, but I am curious what error I have that causes piping not to work.

function Get-MachinesUser{
    param (
        [parameter(Mandatory=$true, ValueFromPipeline=$true)]
        [System.Object[]] $VMArray
    )
    foreach($vm in $VMArray){
        if($VM.Description -match '.*(ut[A-Za-z0-9]{5}).*'){
            [PSCustomObject]@{
            "Name" = $vm.Name  
            "User" = $Matches[1]
            }
        }
    }
}