S Pen problems with connection

Hey! I've been having a few issues with my S Pen for a few weeks now. Most of the time, the phone won't detect if I eject the S Pen. Bluetooth gestures will work but I can't use the S Pen to write, draw or select anything. Another problem is that the S Pen won't connect at all sometimes.

I've contacted Samsung multiple times before without a clear diagnosis. The only thing that helped was soft-resetting the phone. Resetting the S Pen made the problem even worse somehow.

I'm using a third party case without any (visible) magnets (afaik)