Wow. I just stumbled on your post while searching for a solution to the exact same MVFuse issue. Congratulations on a beautiful pool.
Reading your posts was kind of like re-opening a still fresh wound. We used the same pool builder. I don't wish to speak kill of the dead, but I have few kind thoughts for the late majority owner. He really left a lot of people, including his own family, in a world of hurt with his financial shenanigans before taking his own life.
We started our build in December and were supposed to be done by May. They got us to tile and coping before going belly-up. We ended up buying our equipment online and lining up our own subs to finish the plaster and startup. We're out about 2x-3x what you were, but plaster was done last week and we're breaking in our new pool now.
In any case, I'm curious about the MVFuse issue and I'm guessing that you had ZERO suction from your main drain, right? I'm also curious whether you were able to get the plumber (I'm guessing we have the same one based in TX) to cover the cost to rip out and replace the decking. PM me if your prefer.