Handling KillSwitch in Akka Streams

I am initializing a stream inside an actor and killing this stream using KillSwitch when the actor stops.
I would like to close existing connections in my custom source of the stream when shutting down the stream but the postStop method is not called, am I missing something?

postStop should always be called when the stream is shut down, regardless if it is graceful or an “abrupt termination” (shutting down the materialiser or actor system) so this sounds very weird.

Do you have a minimal reproducer you can share?

I will try making one, but today it seems like working.
I’ll try giving it a deeper look