PerlBrew
has a bug(85493) noted in version 0.63 which has yet to be addressed. I spent a good 2.5 hours trying to figure out why 'perlbrew list-modules' didn't return anything. Finally found the the problem in the bug list at RT CPAN. The actual cause of the problem was pointed out Here on github.

In simple terms: the command 'list-modules' will not work if you are use'ing or have switch'ed to an alias.

You must use the full name of the Perl dist you are using as is shown in 'perlbrew list' or 'perlbrew available'. (See Update below for alternative)

Perlbrew is fantastic! (minor rant) It is a bit disappointing that this ticket has been around for 11 months without being addressed. It is not an obvious(to me) issue to find or address. My searches(both here and google) rendered very little. The docs here don't make any mention of this either.
My hope is that someone may save themselves some time finding this here when faced with this issue.

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Note:

Was unsure where to post this, but based on FAQ Re: Posting this seems the best place... please correct me if not.

Update:

Found a workaround listed Stack Overflow which states that when installing a Perl via PerlBrew, one can use the '--as' install option to name the Perl install, accomplishing something like the alias command would. While it is good to know how to work around this problem, I would still rather have the 'alias' command work. I don't always know ahead of time what I might want to name a given install.

Replaced the  <br> with  <p> for readability.