The title says it. The vocals reduction and isolation effect changes absolutely nothing. I use this effect very often for my edits, so this is a real bummer.
That effect is always dependent on the source material …
https ://manual.audacityteam.org/man/vocal_reduction_and_isolation.html#limitations
I know, it was my most used effect. But since 3.x it just doesn’t work any more. It calculates, but does not do anything.