I posted the following message to help-gnu-emacs and should demonstrate
the possible bug. (Please note that I made one minor correction, i.e.-
"buffer" instead of "butter."
> emacs version GNU Emacs 28.0.50 (build 344, x86_64-pc-linux-gnu, GTK+
> Version 3.24.23, cairo version 1.16.0) of 2020-12-31
>
> I have a buffer "learnabbrev.txt" open with abbrev-mode enabled,
>
> and in my init file,
>
> (setq abbrev-suggest t)
> (setq abbrev-suggest-hint-threshold 0).
>
> My (global-abbrev-table) includes:
>
> "foo" 1 "find outer otter"
>
> (I checked to make sure that foo expanded to "find outer otter.")
>
> When I start to enter "find outer otter," and no matter how many
> letters I enter, including the entire phrase, there are no suggestions
> in the echo area.
>
> If I understand the info entries for abbrev-suggest and
> abbrev-suugest-hint-threshold, should not a hint show in the echo
> area, even after I type the first "f?"
Best,
Charlie Millar