I didn’t correct this in my first reply, but chains and streams are not the same thing. If you have a chain that has failed, then it is likely a hardware problem. If you have a stream that is inactive, that is an indication that rate adaptation is doing its job.
Single channel mode usually uses 2 streams, but may drop to one stream if RF conditions are poor. Dual channel mode uses up to 4 streams. You may also see the number of streams change periodically because of tests that Rate Adaptation performs to optimize performance. This is normal, and not a failure.