I'm not dealing with an ongoing problem but trying to learn from people with more experience so that I can be more efficient in the future.
If you disconnect the PV wires from the controller and measure amperage across the wires and get an appropriate reading for the PV array - does that completely eliminate the PV wiring and array from being a possible cause of whatever issue? I know that voltage can go through wiring that is not really capable of carrying substantial current - but unless there is something I don't know substantial current really can not - in my experience, it will arc and/or burn the bad/inadequate wire or connection and usually just make it completely inopperable.
Is there something about this I just don't know? If not, it seems like this one measurement would eliminate a lot of possible causes of a charging issue.