4IFIR comes as a full package (Atmosphere, Hekate, sigpatches etc.), so after fully switching my homebrew setup to it, it has always worked with FW 16.0.3.
1.5 and 1.6 are pretty old at this point, so maybe if your emuNAND is on FW 16.1.0, you can't boot them.
Btw August update:
I have fully finished the game on update 1.2.0 using 4IFIR 1.6 (June 15th) and later 1.5, with the graphics plugin version of the graphics mod. 1.6 (June 15th) was 99% stable, but after long gaming sessions my Switch could sometimes restart randomly during gameplay. 1.5 was 100% fine.
https://gbatemp.net/threads/the-legend-of-zelda-tears-of-the-kingdom-graphic-mod-plugin.636153/
November update:
It's not a good idea to use 4IFIR these days:
https://gbatemp.net/threads/4ifir-vs-switch-oc-suite-real-benchmark.642354/page-9
I would go with OC Suite now.
As you can see back then I needed to use a really old version of 4IFIR for it to stay 100% stable.
1.5 and 1.6 are pretty old at this point, so maybe if your emuNAND is on FW 16.1.0, you can't boot them.
Btw August update:
I have fully finished the game on update 1.2.0 using 4IFIR 1.6 (June 15th) and later 1.5, with the graphics plugin version of the graphics mod. 1.6 (June 15th) was 99% stable, but after long gaming sessions my Switch could sometimes restart randomly during gameplay. 1.5 was 100% fine.
https://gbatemp.net/threads/the-legend-of-zelda-tears-of-the-kingdom-graphic-mod-plugin.636153/
November update:
It's not a good idea to use 4IFIR these days:
https://gbatemp.net/threads/4ifir-vs-switch-oc-suite-real-benchmark.642354/page-9
I would go with OC Suite now.
As you can see back then I needed to use a really old version of 4IFIR for it to stay 100% stable.
Last edited by Ethelbert,