Pylontech US5000 & 48/5k Quattro not Charging on 15A Circuit

Hello. I recently got a VE Configure question answered on here, so I thought I would follow up with another technical (for me) question.

System:
x2 Quattro 48/5000-120v Split Phase (latest firmware)
x4 US5000
x2 250/100 MPPT (14kW Solar)

This system has been working very well. However, during testing, I noticed that when SOC was lowered to around 10-15% and 48V, the system would not accept charge from a 15A Circuit (or a normal extension cord in NA). I utilized a 15-50A Adapter to plug into a 50A RV/Generator Twist Lock Input and I am seeing 120v on both L1 and L2 as read via a Multimeter and Cerbo, but for some reason the Low Battery signal from BMS/Quattro wont let the Inverters turn on and start charging. Oddly enough, this does not occur when I plug into the 50A Outlet at the shop or if above 15% SOC. It is only on 15A Circuit, below 15% SOC.

A few theories.

  1. The 15-50A Adapter is splitting L1 voltage across L1 and L2 and as a result the 15A current is being split across both Quattros, thus the AC Current in the Leader is not above the minimum configurable 13.4A Current Limit and does not charge the batteries. This does not make sense, because again, it does charge above 15% SOC.
  2. VE Configure Programming. I feel I have exhausted every possible programming option in Configure and still don’t know what it could be. Right not my programming is this:
    -Switch as Group is Off
    -2-Phase 180d return to floating
    -Low Shut Down V = 44v
    -Low Restart and Pre Alarm V = 48v
    -No VS or Assistants
    -Charger Enabled
    -Weak AC off right now (tried turning on too, no help)
    -Attempted using Assistance to force it to charge (no help)
    Is it something in the programming?

I have contacted my Pylontech Dealer for assistance and am still waiting to hear back.

Any help would be greatly appreciated.