Everything you said sounds reasonable. And could be a proper explanation about what happened.

I will say it was a mistake to have installed the system originally 'without' a MoCA filter to begin with. You should never do that. MoCA 101.
I keep a bag of them on the van, they are cheap.

Your post highlights a problem we have all been dealing with for many years now. Everything is software driven these days. Many times we have no access to and are not allowed to diagnose or program the devices that are installed everyday. Everything is built to be plug-in-play and when that doesn't happen, people in the field (installer & customers alike) often have no recourse to do anything about it.