This problem affects at least releases 1.2.8, 1.3.1 and 1.3.2.
In src/tools/hunspell.cxx, when the program is invoked using hunspell -a, method suggest is invoked near the case label 'case PIPE:' as
pMS[d]->suggest(&wlst, token)
It should be invoked as
suggest(&wlst[k], chenc(token, io_enc, dic_enc[d]))
This is how the method is usually invoked within this file.
A consequence of this bug is that when communicated with in UTF-8, useful suggestions are not generated from an 8-bit dictionary.
Also in hunspell 1.3.3.
$ echo 'atanció' | hunspell
Hunspell 1.3.3
& atanció 6 0: natació, atenció, anotació, incitació, ancianitat, anunciata
$ echo 'atanció' | hunspell -a
@(#) International Ispell Version 3.2.06 (but really Hunspell 1.3.3)
& atanció 1 0: ancianitat
I think this is now fixed in master for >= 1.3.4