I'm having the same issue and I have yet to find a solution. I was struggling with luma initially but I got it working, now this isn't working for me and its a little frustrating.
Edit: It seems to be working now, I had to download and run the .cia linked on another thread. You'll need to run it with FBI again but you probably already knew that. I can't post links because I'm a new member, and since somebody already linked the download I'm just going to space that thread out here. https: //gbatemp.net/threads/ntr-boot-selector-with-11-8-compatibility.513537/