Phantom miss issues - 2014 6.2l Jetboat

Hi guys, long time stalker, first time poster.

I have a customr who has got a 2014 SS cammed camaro 6.2l Engine in a jet boat. (running mafless)

I did the base tune setup for them as they are more versed in aftermarket Ecus than the E38.

Issue is, they have now had a tuner do the final touch ups on the water but keep having this strange issue that only happens at one load/rpm/tps.

What happens is the engine completely drops torque at around 4400rpm until around 3600ish.

Map remains somewhat stable, Iats stable, Rpm drops steadily, tps commanded and actual remain steady, TAC stays steady. Only thing that tells some sort of story is that the Airmass peals off to 0, and the advance rockets to the first column of the advance table. Always comes back at same RPM.

Things that have been either maxed or mined to suit the jet boat setup that may affect

Knock sensors off, burst off, torque management off, spark ETC and fuel cuts turned off ( to eliminate them being an issue) etc.

We have gone through pretty much everything and cant seem to see whats causing it!

Any help would be much appreciated, as their customer is getting frustrated as expected

Attached is tune file and also one log that you can see the issue at end. i have other logs he sent me that show it happening more often however they are missing some PIDs like Airmass so hard to cross reference