vim - replace is broken for specfic extension(s)

[buggyfunbunny]

12.0.3/hf31  and some user macros from this group (but I'm not sure which ones, alas)

for .sql files (derives from db2), at least,

global search and replace  %s/x/z/g
always returns string not found
ignorecase is on

any idea where to look?  I just don't recall which user fixes I've installed.  dang.

S & R from the menu does work, so all is not lost.  I just rather use the command line.