AFB is enabled, speed is set, but I don't see the blue marker on the HUD speedometer for AFB. DB BR101
Did you unlock the brake key BEFORE you activated AFB? If not, unlock the brake key then zero the AFB lever and disable AFB then turn them on again.
Look here for the 101 updates that have been made. Page 2 also includes future updates coming (not released yet, but going to with the next tsw update https://forums.dovetailgames.com/threads/tsw3-br101-changelist.58759/