F11 (Styles) window vanishes. Impossible to get back.

Product now unusable to me. Can’t work without using styles !!!
Regression present and reported since at least two versions.
Anyone knows whether Apache OpenOffice is a bit better / more usable ?

Regression present and reported since at least two versions

Mind referencing the report, instead of just declaring?
F11 works for me by opening the sidebar with Stylist. Also you mention something about it being unusable and displaying in wrong mode since long ago. Please also mention relevant reports, or at least, steps to reproduce.

You didn’t search very hard.
This is exactly the problem.
Luckily someone has posted a way to recover… temporarily.

I didn’t search at all; why should I? I’m used to claims that aren’t based on something substantial, like this one: the problem is only reported for the last version (6.0), and not “since at least two versions” (the third number isn’t version). It has been bisected, and three devs are in CC list, the one who introduced regression among them. The version it happens in is Fresh, that is recommended for early adopters … exactly to find and fix regressions until the version becomes Still.

Answering my own second part of the question : I just installed and tested OO and it seems to be much less buggy. The styles & formatting window is there, much more usable and directly displaying in the right mode (something that got lost in LO long ago).
Is there hope to see the innumerable regressions and bugs introduced in LO get fixed eventually ?