450 downlink signal oddity

We have been seeing a weird issue with one of our 5GHz 450 series access points.  The uplink seems to be ok, but the downlink has a significant difference of signal between the vertical chain and the horizontal.  The real oddity here is the signal to noise on the downlink continues to say it is good and strong on both chains.  Customers have had issues of constant disconnects and poor speeds.  We have tried different firmwares (but eventually settled on 13.1.3 for stability and timing with other WISP's in the area); and we've tried changing frequency.  We have a crew heading up to the tower in a few days to check the hardware, but I figured to ask if anyone else has ever run into this.

Here are a few examples snipped from the Link Status of the AP

We've seen something like this with water that somehow got into one of the RF cables. It showed a pretty big mismatch between chains. Just to be safe, I'd probably head up to the site with a new AP, new RF cables, and possibly even a new antenna.

Thanks for the quick response.  We also have had lots of issues with water getting into the LMRs on the 450 APs.  However, usually when this happens, it messes up both the uplink and downlink on that affected chain.  Additionally, the SNR takes a dive too.  I can't argue that it is a real possiblity, but I am more concerned about having to replace the AP.

Do the SMs show the same signal strength and S/N in this GUIs?  I've found the APs Link Status page is pretty unreliable.

You could also try a link capacity test with Signal to Noise Ratio Calculation checked.  If it is an issue with water in the antenna connector, you'll see it in the modulations being used.

OK, weird. It's not just me. I have various 3.6 and 5GHz 450 sectors that show strange imbalanced power levels like this too. Some show it on the uplink, others on the downlink. But as you say, the SNR looks normal. Exactly the same here. I wonder if this is some calibration issue.