To parrot this post
Its because you did not use the -x option (or -c option)
pp -x ...
pp -c ...
See also Re: Problem in creating exe using PAR module, Re^2: Packaging Perl Programs (is) Painful, Re: Building a Mojolicious app with PAR::Packer
$ pp -e " use Package::Stash; print qq{$_\n} for keys %INC; "
$ a.exe
Could not find a suitable Package::Stash implementation: Can't locate Package/Stash/XS.pm in @INC ...
$ pp -c -e " use Package::Stash; print qq{$_\n} for keys %INC; "
$ a.exe
attributes.pm
Compress/Raw/Zlib.pm
List/Util.pm
File/Find.pm
Cwd.pm
IO/Uncompress/Adapter/Inflate.pm
Package/Stash/XS.pm
Carp/Heavy.pm
...
Package/Stash.pm
...