I'm quite sure your timing is bad. The keys should work.
Describe exactly what you do and when.
I was finally able to enter in recovery mode, uninstall magisk 17.0 and install magisk 17.1.
The method has been power and vol down till Lg logo, releasing all, then vol up and vol down.
My error was about not releasing vol down after first step.
Thanks to everyone for suggestions and apologizes for the amount of posts.