Probably because you are using DSP FX within the instruments?
See https://forum.renoise.com/t/done-3-1-instruments-with-fx-are-tied-to-one-track/40268 please for an explaination and related discussion please.
Oh no… i’ve read all… no sense, confused to death. p.s. This limitation-by-design somehow reminds me of my own weird one - i still cant write and operate in traditional DAW (a traditional way - horizontal from left to right), i’m stuck with those vertical from top-to bottom hexadecimal shit. Otherwise i would already learn Live lol. Anyway, can’t wait what future holds for Redux & R3.1