The code you show can't be the code you're running.

A reduced version of your code dies with an error for me:

use strict;
use warnings;

my %seen = ();
my $flag = 0;
my (@nonprod_lpars, @lparstat, $clntdir);
my $regexp_2_skip = qr/entitled capacity of pool/i;
my $regexp_2_get  = qr/entitled capacity|desired Virtual CPU|desired M
+emory|online Virtual CPU|maximum Virtual CPU|maximum memory|online me
+mory/i;
my @asof;

sub _ce {

print "IN CE SUB\n";

    die "no parameter!\n" unless @_;
    my ($ce_ref) = @_;

    for my $name (@{ $ce_ref }) {
        #@asof = +(split("/", $name, 0))[-3,-2,-4];
        #$lpname = +(split("/", $name, 0))[3];
        #print $csv "$lpname\n";
        #print $csv '*' x length($lpname),"\n";
        #print '*' x length($lpname),"\n";
        print "$name\n";
        open (my $i, "+<", $$name) or warn $!;   ### FAILS HERE ###
        while (<$i>) {
            chomp $i;
            next if $i =~ /$regexp_2_skip/;
            next if $i !~ /$regexp_2_get/;
            ($i) =~ s/:/,/g;
            ($i) =~ s/\s+//g;
            #print $csv "$i,\n";
            print "$i,\n";
        }
    }
    #print $csv "\n\nHost,Entitled CPU and RAM as of,\n\n";

return;
}

@lparstat = ('1','2','3');
_ce(\@lparstat);
[download]

Either you slapped use strict; at the top of your program without re-running it, or you are running other code than the code you are looking at.

Running your program with use strict; immediately lets Perl tell you what goes wrong. Another hint would be to actually print the filename you're trying to open:

        open (my $i, "+<", $$name) or warn "Failed to open '$$name': $
+!";   ### FAILS HERE ###
[download]

If you're not using strict, Perl will allow you to dereference things that are not a reference. This rarely makes sense but you will actually see the contents of $$name (nothing).

Maybe that is just a typo and you wanted to use $name instead.

the correct code is yes w/out $$name rather using $name i always use strict and warnings. its there in the code at the top.

sub _ce {

print "IN CE SUB\n";

    die "no parameter!\n" unless @_;
    my ($ce_ref) = @_;

    for my $name (@{ $ce_ref }) {
        @asof = +(split("/", $name, 0))[-3,-2,-4];
        $lpname = +(split("/", $name, 0))[3];
        print $csv "$lpname\n";
        print $csv '*' x length($lpname),"\n";
        print '*' x length($lpname),"\n";
        print "$name\n";
        open (my $i, "+<", $name) or warn $!;  ### FAILS HERE ###
        while (<$i>) {
            chomp $i;
            next if $i =~ /$regexp_2_skip/;
            next if $i !~ /$regexp_2_get/;
            ($i) =~ s/:/,/g;
            ($i) =~ s/\s+//g;
            print $csv "$i,\n";
            print "$i,\n";
        }
    }
    print $csv "\n\nHost,Entitled CPU and RAM as of @asof,\n\n";
return;
}

__OUT__
SCALAR NPLPARS 30 SCALAR lparstat: 30
IN CE SUB
********
/opt/r2configs/edidev00/2018/03/13/lparstat-i.out

No such file or directory at get_nonprod_AIX_resrcs_used.plx line 454,
+ <$lus> line 131.
readline() on closed filehandle $i at get_nonprod_AIX_resrcs_used.plx 
+line 455.
**********
/opt/r2configs/ediperqa00/2018/03/13/lparstat-i.out

# ls -l /opt/r2configs/ediperqa00/2018/03/13/lparstat-i.out
-rw-r--r--    1 root     system         2219 Mar 13 21:00 /opt/r2confi
+gs/ediperqa00/2018/03/13/lparstat-i.out
[download]

$i is not a good name for a filehandle, it's easy to get confused with the file contents.

   open (my $i, "+<", $name) or warn $!;   ### FAILS HERE ###
   while (<$i>) {
     chomp $i;
     next if $i =~ /$regexp_2_skip/;
     next if $i !~ /$regexp_2_get/;
     ($i) =~ s/:/,/g;
     ($i) =~ s/\s+//g;
     print $csv "$i,\n";
     print "$i,\n";
   }
[download]

as Toolic said, you probably have line endings on $name from find. Try

sub _ce {
    print "IN CE SUB\n";

    die "no parameter!\n" unless @_;
    my ($ce_ref) = @_;

    for my $name (@{ $ce_ref }) {
        chomp $name;
        @asof = +(split("/", $name, 0))[-3,-2,-4];
        $lpname = +(split("/", $name, 0))[3];
        print $csv "$lpname\n";
        print $csv '*' x length($lpname),"\n";
        print '*' x length($lpname),"\n";
        print "$name\n";
        open (my $fh, "+<", $name) or die "Could not open '$name' $!";
+  ### FAILS HERE ###
        while (my $line = <$fh>) {
            chomp $line;
            next if $line =~ /$regexp_2_skip/;
            next if $line !~ /$regexp_2_get/;
            $line =~ s/:/,/g;
            $line =~ s/\s+//g;
            print $csv "$line,\n";
            print "$line,\n";
        }
    }
    print $csv "\n\nHost,Entitled CPU and RAM as of @asof,\n\n";
    return;
}
[download]

poj

chomp @lparstat;
[download]

        print $csv "$lpname\n";
        print $csv '*' x length($lpname),"\n";

            print $csv "$i,\n";

    print $csv "\n\nHost,Entitled CPU and RAM as of @asof,\n\n";
[download]

$csv is not a valid FILEHANDLE. It has not been opened anywhere so it cannot be printed to.

        open (my $i, "+<", $name) or warn $!;   ### FAILS HERE ###
        while (<$i>) {
            chomp $i;
            next if $i =~ /$regexp_2_skip/;
            next if $i !~ /$regexp_2_get/;
            ($i) =~ s/:/,/g;
            ($i) =~ s/\s+//g;
            print $csv "$i,\n";
            print "$i,\n";
        }
[download]

The variable $i is first used as a FILEHANDLE and then used as text from a file. But in the line while (<$i>) { you are assigning the file text to the variable $_ which you don't use at all.

apologies, csv is opened in the code. i forgot to paste it. the error says $i and $i is not being opened that csv FH.