Solar panel charging issue

Apologies if this issue has been addressed before - but I couldnt find reference to it in the archives.
Just getting round to testing solar charging on AC200P i bought in Fall of 2021.
I have 3 Renogy 100 watt fixed panels wired in series connected to the AC200P by about 10 feet of AWG 10 cable. The multimeter tells me the output of the panels is about 10 times what the AC200p displays. For example, at noon today the output at the end of the adapter cable was about 59 volts with 4.5 amps - say around 260 to 270 watts of potential input. When I plug in the cable for PV charging, the display gives me the expected voltage (say 50 to 60) but a much reduced expected amp and watt count (.5 amps with maybe 20 to 40 watts showing on the charging display)
What is going on here?
AC charging works as expected and all other aspects of the unit are pretty much as expected. The only other hitch I experienced with pv charging is that the unit came set with 12 volt car charging as default and threw an over voltage error the first time I plugged in the panels - this was easily remedied though (why does a sogen come with car charging as a default setting).
Any thoughts or suggestions appreciated.