This is not a bug. You need to turn off “Adjust opacity instead of fade with black” in the Filters panel. When adding a fade to a clip on a track above V1, it fades opacity by default. You basically have the same image on V2 as V3, so it looks like it is not doing anything.
You do not add a new Opacity filter. The Fade In Video and Fade Out Video filters have a checkbox that says in English: “Adjust opacity instead of fade with black”
First you add the fade-in and then turn off the checkbox.
Or, instead of putting that video on V2 or V3 put it on V1 since you do not need track blending.