Recently I ran across a few articles with tips on how to more efficiently use bash that mentioned a combination I'd never tried: Ctrl-S (in the prompt, with no command running) to search the other way from Ctrl-R. Since I use Ctrl-R a lot, this was interesting.
However, I can't get it to activate on any bash installation I have access to (Mac OS Catalina, Git for Windows, Debian 10 over ssh, NixOS over ssh). Since most of them have various customizations that might interfere, I also tried
--noprofile --norc, to no avail.
In each case, I of course first select a suitable line in history so that there's a "forward" to search, then try the key chord, but nothing happens. (Not only is there no prompt, typing any characters just puts them into the line without searching.) Likewise with Ctrl-R first to find something.