The image on the left is the RF Chains (physical or PHY layer), while the image on the right is the Streams (MAC layer). Missing Rx power (on the left) is the cause of the missing streams (on the right). These both indicate that the radio is sending and receiving on the vertical polarization only.
Most often, we see both chains of the same polarization fail due to cabling problems such as tight bends or water ingress. The problem could also be an obstruction in the horizontal polarization, or a radio transmit or receiver problem (Tx or Rx).
To determine the cause, swap both ends of the RF cables between horizontal and vertical polarization. If the problem follows the cable, replace the cable. You may also need to perform this step on the opposite side of the link.
A more complete troubleshooting guide can be found here:
I don’t think the following is the problem, but another reason for dropped chains with a single channel on one end of a link is the dual-link feature. People sometimes confuse missing chains for a hardware problem, when the radio is dropping chains with heavy interference intentionally: http://backhaul.help.mimosa.co/backhaul-faq-dual-link