Megolm Session Key differs between m.room_key and m.forwarded_room_key

[patrick-scho]

Hello, I hope this is the right place to ask this question.
I am building a Matrix client library and I'm trying to decrypt group messages.
Currently I am testing this using the Element web client, but as far as I could tell they use this library.
I am using the C libolm, hopefully you can still help me.
When I receive a new message, an m.room_key event is sent, and I can create my OlmInboundGroupSession and decrypt the message.
But when I try to decrypt a past message and send an m.room_key_request, I get an m.forwarded_room_key event, and the session key is different from the one I initially got.
I noticed that the key has a length of SESSION_EXPORT_RAW_LENGTH instead of SESSION_KEY_RAW_LENGTH, so I tried using olm_import_inbound_group_session instead of olm_init_inbound_group_session, which seems to successfully initialize the session, but then I am not able to decrypt the message and I get a BAD_SIGNATURE error.
I tried looking at how room key events are handled in this library, but it looks like m.room_key and m.forwarded_room_key are handled the same way, which is what I wanted to do as well.
I'm guessing this is some stupid oversight on my part, but I couldn't figure it out, so I'm hoping someone can help me out.

[EnglanM]

@patrick-scho did you solve this issue bro?