Adding to a dictionary containing custom classes fails

[OtterKring]

Prerequisites

• I have written a descriptive issue title.
• I have searched all open and closed issues to ensure it has not already been reported.
• I have read the troubleshooting guide.
• I am sure this issue is with the extension itself and does not reproduce in a standalone PowerShell instance.
• I have verified that I am using the latest version of Visual Studio Code and the PowerShell extension.
• If this is a security issue, I have read the security issue reporting guidance.

Summary

I created the following class:

    class MailboxTypeStatistics {
        [string] $Type
        [UInt32] $Count = 0
        [UInt64] $Size = 0

        MailboxTypeStatistics ( [string] $Type ) {
            $this.Type = $Type
        }

        [void] Update ( [string] $TotalItemSize ) {
            $this.Count++
            $this.Size += [uint64]( $TotalItemSize.ToString().Split('(')[1] -replace '\D+' )
        }
    }

then created a generic dictionary:

$dir = [System.Collections.Generic.Dictionary[string,mailboxtypestatistics]]::new()

then I tried adding a key like this:

$dir.Add('UserMailbox',[MailboxTypeStatistics]::new('UserMailbox'))

and received the following error message in the VSCode Powershell Extension Console:

MethodException: Cannot find an overload for "Add" and the argument count: "2".

I tested in the standard console (Windows Terminal) and it worked without issues.

PowerShell Version

PS> $PSVersiontable; $Host

Name                           Value
----                           -----
PSVersion                      7.5.0
PSEdition                      Core
GitCommitId                    7.5.0
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Name             : Visual Studio Code Host
Version          : 2025.3.0
InstanceId       : 48fea0c2-4384-431c-b4fc-72a04d695da0
UI               : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture   : de-DE
CurrentUICulture : en-US
PrivateData      : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
DebuggerEnabled  : True
IsRunspacePushed : False
Runspace         : System.Management.Automation.Runspaces.LocalRunspace

Visual Studio Code Version

PS> code --version
1.99.1
7c6fdfb0b8f2f675eb0b47f3d95eeca78962565b
x64

Extension Version

PS> code --list-extensions --show-versions | Select-String powershell

[email protected]

Steps to Reproduce

see "Summery"

Visuals

No response

Logs

No response

[SydneyhSmith]

@OtterKring we are having trouble reproing, can you confirm you are still seeing this? Does this repro in the non-integrated terminal? Can you also double check the type of $dir?