Stacked Rosies shut down

[Wirenut]

I installed a system with 2 stacked Rosie inverters back in the spring. It seemed to occasionally shut off for no reason. I spoke to someone at Mid Nite about it and was told there was a bug in the firmware that made them shut off when the temperature went below 32 degrees and it needed to be updated.
I updated it to 25.2.13 after that and the system seemed to work well.
2 weeks ago we installed a generator on this system. While I was there I decided to update the FW on the equipment. (Maybe I should have left well enough alone.) I updated the inverters to 25.9.9 in both of them. I tried to update the MNGP2 but it failed a couple times so I gave up and left it at 25.3.27.
I visited the site 13 days later and the inverters were off. When I tried to turn them on with the MNGP2 there would be a very brief electrical buzzing noise and then the setting would go back to off. This happened either turning both on or individually, even with the AC breakers off so they weren't connected. I then power cycled the battery breakers off for a moment and turned them back on. Both inverters rebooted and started making power. When I left they were collectively supplying about 2,500 watts to the cabin. The new generator had about 14 hours on it so I know it has auto-started a time or two in the past two weeks so the system must have been working for a while after I left.
I know I didn't fix the problem. I'm sure it will happen again. What do you recommend?
Do I need to update the MNGP2? Should I revert the inverters back to the previous firmware?

The batteries are 2 Powerflow16 and the charge controller is a Classic 200 if that matters.

Thanks for any help you can give.