I found that I can not set both NDI and fullscreen out on Multiview mode?
why?

Nope

I am using 4k version and found this issue

Basically what's happening in this situation (if its the same as ours) is that we would like to be able to do two things. 1: Set one of our fullscreen outputs to multiview. 2: Set an NDI output to also have multiview. Currently what happens is once we set an NDI output to multiview, we are no longer able to change the fullscreen output to multiview. It stays stuck on whatever the output window is showing.

I haven't seen any other posts on this so i apologize if this was previously answered/fixed but I was wondering if this is just a limitation in vmix or if there's something i'm missing to set it up properly. Thanks!

I know of lot of good reasons to have Multiview via NDI. Basically shows all your cameras in one one image and send via network instead of HDMI or SDI cable. Could be handy for replay or sending to another room for production.

But you could make you own multiview on a input with the 10 overlays and send that as NDI input. Probably add some extra load though on your computer. But does work fine.
- Create colour input with transparency. Then add all your cameras or inputs youy want to the overlay channels then select one the grid templates for layout.
Then in Vmix settings > Outputs > NDI (choose one of the External outputs to use and turn on NDI) Select the input you created. You will now have a custom multiview output over NDI\\

I can enable Muliview on local second monitor and on external 4 (pro version) send that to NDI > Working fine with no problems.

Ok update: External 1 can not be used with Multiview and NDI at the same time but 2 - 4 can be used at the same time.

I think he means only one multiview display, yes, you can have that one display show up on multiple outputs, like NDI, external, fullscreen etc. I have run into this as well, where I like the 2x8 multiview, but have more than 8 sources, so I'd like a second multi view screen for the other stuff I need to monitor.

While I'm aware you can make an input and make this a multiview according to what you want, but this doesn't give you Tally or things like video remaining time that we get on the primary multiview. Its a work around but not a perfect solution.