While I do greatly appreciate Voxels work and contributions, and despite having used his firmwares in the past, this isn't something he can fix.Might contact NG support about it. If not, say on .52 or try Voxels FW.
Since his latest FW releases are all based on 1.0.2.62, any wireless radio issues in that will also be part of his firmwares.
Unfortunately the fact that the issue only affects some, and not all users brings me to think that NG simply doesn't care and we won't see a new FW version for a while.
I'm sticking to OpenWRT now, but I'll be leaving for college in September, and I would ideally like my parents to have a carefree setup on both R7800s, which I can only achieve with stock FW since they're super stable. They're nowhere near capable enough to diagnose and fix issues with custom FWs if they were to arise.