cache-clean cannot read from config file

On 158.39.75.142 and ARC 6 testing machine, it seems cache-clean can not find arc.conf or the caches:

sudo /usr/libexec/arc/cache-clean  -s
No config file found and no caches specified

If I do

sudo /usr/libexec/arc/cache-clean -c /etc/arc.conf -s 
No caches found in config file '/etc/arc.conf'

From arc.conf:

[arex/cache]
cachedir=/wlcg/cache
cachesize=50 40
cachelifetime=60d
#cacheshared=yes

[centos@frontend001 ~]$ ls -lhrt /wlcg/cache/
total 8.0K
drwxr-xr-x 16 root root 4.0K Apr 21 20:16 data
drwxr-xr-x 12 root root 4.0K Apr 21 20:17 joblinks

However, cache-cleaning seems to work:

[centos@frontend001 arc]$ ls -lhrt  /var/log/arc/cache-clean.log
-rw-r--r-- 1 root root 57K Apr 21 20:31 /var/log/arc/cache-clean.log

[centos@frontend001 arc]$ sudo tail -n 5 /var/log/arc/cache-clean.log
[2018-04-21 20:29:36] [cache-clean] [INFO] [27433] /wlcg/cache: used space 14 GB / 19 GB (72.75%)
[2018-04-21 20:29:36] [cache-clean] [INFO] [27433] Cleaning finished, used space now 14 GB / 19 GB (72.75%)
[2018-04-21 20:31:24] [cache-clean] [INFO] [29464] Cache cleaning started
[2018-04-21 20:31:24] [cache-clean] [INFO] [29464] /wlcg/cache: used space 14 GB / 19 GB (72.80%)
[2018-04-21 20:31:24] [cache-clean] [INFO] [29464] Cleaning finished, used space now 14 GB / 19 GB (72.80%)