inexplicable packet loss with loopback communication

[amdfxlucas]

I'm using lsquic through the nexus-lsquic library from c++ (https://github.com/cbodley/nexus).
My aim is to implement QUIC transport for the cpp-libp2p project[https://github.com/libp2p/cpp-libp2p].

When i run the simple client-server Echo example I get strange unexpected results ( lsquic trace dumps attached ):

• the server(127.0.0.1:40010) receives the client's connection request (127.0.0.1:36725) and processed it
• apparently the server's responses never reach the client due to packet loss

How can this be, if no network is involved at all ?!

I have no reason to suspect a bug in the nexus library , it has always worked so far.
Moreover I use a debug build of the lib, so if I were to use the library wrong, i would trigger the debug assertions (which i do not ).

I know opening an issue for this will probably not be welcomed, but i just dont know where else to turn.

I am very grateful for any help with the interpretation of the log files, I can't make much sense of it on my own.
(Please let me know if you require additional data, i.e. an strace log )

client_log.txt
server_log.txt