Just tested 397.93, and I have good news and bad news:
Good news is that your friend delivered (partly) in 1080p23 for 3D (I didn't test 2D). I now get 13min between frame drops, which is a significant improvement compared to the 3-5min of previous drivers (at least those I had tested).
Bad news is that the levels are still borked, however I found why I have the issue and many others don't: the levels are only borked in 12bits, not in 8bits. So it looks like between the banding in passthrough and the borked levels, nVidia shows little love for their 12bits setting.
You would think that the solution is easy: use 8bits in the GPU... Well, That works fine for 2D and 3D SDR, unfortunately HDR is borked in 8bits on the JVCs and you get at all refresh rates (at least in UHD) the magenta bug that I only have on 4K60p with previous drivers. The only way to get rid of it is, like with the 4K60 magenta bug, is to disable the "send HDR metadata", which as you know is a no no for me until we get the ability to switch HDR profiles according to max brightness with pixel shader, as the Vertex relies on this to select my custom curve. It is, however, a viable workaround for those whose display doesn't need HDR Metadata.
So pick your poison:
385.28: everything works but 1 frame drop every 3-5min in 3D.
397.93: better 3D (13min between frame drops), Asio4all compatibility still broken, levels borked in 12bits, HDR borked on JVCs in 8bits.
Aaaargh!
Thanks a lot for your efforts and your friends though, but I'm back to 385.28 if I don't find a way to get rid of the magenta bug in 8bits, at least until I can switch to pixel shader.
I'll let others reply. The AVS thread is indeed reserved to ongoing work on MadVR's HDR to SDR conversion with pixel shader for projectors, and it's not a support thread for MadVR projector users either, at least not at this stage, as it's a work in progress. HDR10 is a grey area because there is no standard and every display is different.
So I suggest you post your display model and hope that someone can make suggestions for you.