Reproduction: Get some commits list, feed it to tig --stdin, then try using search (pressing / and entering a search string) — no echoing back is expected during typing in.

% tig -v
tig version 2.5.5
ncurses version 5.7.20081102
readline version 8.1

One more thing: what is --no-walk, seemingly there's nothing about it in man except an excerpt showing its use with --stdin:

% man tig|grep walk
           $ tig --no-walk --stdin < cherry-picks.txt
%