I kept getting the error 52 numerous times as well with daily outages, and it was quite frustrating. Mine *appeared* to be related to having low soc on one or more batteries in the bank, but initially I did just have one PV string going to one inverter, as I was waiting for parts to finish building my second array out. What I did that fixed my error 52 was to remove the EG4 setting from both inverters, set them both to USR mode, and then configured the charge settings based the EG4 battery recommendations. After doing that, it fixed both my Error 52 and Error 61 issues. With that said, now I want to see if I can figure out the timeframe to which I connected the second PV string, vs making the settings changes on the inverters - even though you've already shown that it can function with a single PV string connected to just one inverter (as it should).
Not sure if you already got a replacement unit, but if not, it's easy enough to try.