question

@Brett, have you checked the wiring on the starboard side - both between panels and controller as well as between controller and battery?

PV voltage on both controllers looks correct (making an assumption that you have two panels in parallel connected to each controller) but the current (A) between starboard controller and panels looks to me like only one of your panels on that side is really sending current... which, coupled with your statement that sometimes both controllers seem to be doing what they should, makes me suspect that you have a loose connection or poor crimp somewhere on the PV side at one of your panels that may function normally until (as loose connections do) it generates enough heat (resistance) on that line that only the other panel is sending current.

If it was me, I'd grab an IR temp sensor or a FLIR cam and go over the wiring between starboard controller and panels (while they're running hard) and look for a hot connection somewhere along the line... if you find one, it'll be a loose connection that can be tightened or re-crimped. This would include checking the MC4 connectors, if you're using them, as I've seen more than a few of them that are either poorly crimped to begin with, or aren't making a great connection at the pins inside, which will, again, generate heat which causes resistance which generates heat, etc.