cpanm -v should show where it's installing the module, and you can use perl -V to see @INC where Perl is looking for modules. Perhaps you have more than one Perl installation on this machine (perlbrew?) or you're using something like local::lib?

Update: Ah, it does seem the distro is at fault here. See swl's posts.

In reply to Re: cpanm says OK but module not really installed (updated) by haukex
in thread cpanm says OK but module not really installed by Anonymous Monk

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