The following code defines two classes (DeckA and DeckB) that differ only in whether they use the features that come with MooseX::AttributeHelpers. The getters generated by Moose for DeckB are not what I expected. Is this a bug or am I misunderstanding how MooseX::AttributeHelpers and MooseX::FollowPBP ought to interact?
My workaround for now has been to avoid using the is argument in such situations and instead declare a reader and writer as needed.
use strict;
use warnings;
my %moose_args = (
    isa     => 'ArrayRef[Str]',
    is      => 'ro',
    default => sub {[]},
);
my %moose_attr_helper_args = (
    metaclass => 'Collection::Array',
    provides => {
        elements => 'get_all_cards',
    },
);
package DeckA;
use Moose;
use MooseX::FollowPBP;
use MooseX::AttributeHelpers;
has 'cards' => (%moose_args);
package DeckB;
use Moose;
use MooseX::FollowPBP;
use MooseX::AttributeHelpers;
has 'cards' => (%moose_args, %moose_attr_helper_args);
package main;
for my $class (qw(DeckA DeckB)){
    my $deck = $class->new;
    print "\n$class\n";
    for my $method ( qw(cards get_cards get_all_cards) ){
        print "$method: ", $deck->can($method) ? 'yes' : 'no', "\n";
    }
}
Output:
DeckA
cards: no
get_cards: yes
get_all_cards: no
DeckB
cards: yes          # Not what I expected.
get_cards: no       # Not what I expected.
get_all_cards: yes