[BUG] Image assets disappear after updating party size multiple

[DutchCoder420]

Describe the bug
Large and small images disappear a few minutes after updating the party size multiple times. This issue does not occur in version 1.0.175 or earlier on NuGet, but it is present in all versions from 1.1 onward.

To Reproduce

1. Create a basic presence with a party and set the large image with a url.
2. Implement a loop that updates the party size every 10 seconds.
3. After a few minutes, the images reset to their default state.

Expected behavior
The images should remain unchanged and not reset to the default.

Desktop

• OS: Windows
• Framework: .NET 8.0
• Library Version: latest

[Lachee]

I am unable to reproduce.
Please reopen if it is still happening with logs and code snippets.

[DutchCoder420]

I am unable to reproduce. Please reopen if it is still happening with logs and code snippets.

I dont have permission to reopen this issue...

Versions tested

DiscordRPC	Result
1.0.175	Large/small image assets stay visible after countless UpdatePartySize calls
1.5.x ->1.5.0.51	Image assets disappear after a few party-size updates

On 1.5.x the image assets vanish after a few updates, leaving only text. No errors are thrown; Discord simply stops showing the image. Rolling back to 1.0.175 restores correct behaviour.

here is a basic console app sample

internal class Program
{
    private const string ClientId = "DISCORD_RPC_TOKEN";

    private static DiscordRpcClient _client;
    private static Timer _partyTimer;
    private static readonly Random _rng = new();

    static void Main()
    {
        _client = new DiscordRpcClient(ClientId)
        {
            Logger = new FileLogger("discord_rpc.log")
            {
                Level = LogLevel.Trace,
            }
        };
        _client.Initialize();

        _client.SetPresence(new RichPresence
        {
            Details = "Testing RPC Bug",
            State = "Waiting image to dissapear…",
            Timestamps = Timestamps.Now,
            Assets = new Assets
            {
                LargeImageKey = "https://i.imgur.com/VxYHUTk.gif",
                SmallImageKey = "https://i.imgur.com/VxYHUTk.gif",
            },
            Party = new Party
            {
                ID = Guid.NewGuid().ToString(),
                Size = 1,
                Max = 100,
            },
        });

        _partyTimer = new Timer(UpdatePartySize, null, TimeSpan.Zero, TimeSpan.FromSeconds(10));

        Console.WriteLine("RPC running – press any key to exit…");
        Console.ReadKey();

        _partyTimer.Dispose();
        _client.ClearPresence();
        _client.Dispose();
    }

    private static void UpdatePartySize(object _)
    {
        try
        {
            int newSize = _rng.Next(1, 100);

            /* 
             * After a few party-size updates, the image assets vanishes from the Rich Presence. 
             * The issue appears only in versions **newer than 1.0.175**—that version (and earlier) retains the image without problems.
             * 1.0.175 works, when switching to version 1.5.0.51 you will see the images vanishes.
             */
            _client.UpdatePartySize(newSize, 100);
            Console.WriteLine($"Party size → {newSize}/100");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"[RPC error] {ex.Message}");
        }
    }
}