Channel closes right after calling transport.start()

Hello, I've been having issues that I did not have before, somehow. I am implementing my own SSH client and SSH server, and they used to connect without any issues until very recently. I tried to revert the code to a state i was positive it was working in, but this issue still raises. I have tried this mainly on localhost.

I tried hacking around to keep the connection going, when the client invokes a shell or creates its own channel, it seems to go through authentication just fine and is able to recieve data from the server. But when the server tries to read from the client, it recieves that data and then the server is no longer able to send any data back. The channel would automatically close if the server tries to... If the client does not attempt to invoke a shell or create a channel, the connection automatically closes right after calling transport.start() from the server's side. I confirmed that it also occurs after authentication.

You can find the project here: https://github.com/LanHikari22/SSH-EmojiSyncer

Start by reproducing the connection using the linked SSH-EmojiSyncer project, focusing on the server-side transport.start() call and the behavior after authentication. Compare the cases where the client invokes a shell or creates a channel with the case where it does neither. Done means identifying why the channel or connection closes and documenting a verified fix.