Got yesterday official confirmation as follows:
From 1 December 2019: change to waiting list requests
Lufthansa, Austrian Airlines, SWISS and Brussels Airlines are harmonising their waiting list process. From 1 December 2019, a waiting list booking will only be possible in the following booking classes:
Economy Class: Y, B, M
Premium Economy Class: G
Business Class: J, C
First Class: F
Existing waiting list bookings in other booking classes will still be honoured after 1 December 2019.