That's a good point.
We have some background on signal strength ratio here: Separate Receive Power for H and V Inputs in PTP 650/700
SSR is a measure of the V signal strength divided by the H signal strength. In this case, SSR is less than -20 dB, meaning that the H signal is more than 20 dB bigger than the V signal. The problem is in the V path.
However, it's not obvious which end of the link is at fault.