Submitting jobs through internal plugin when running arex as root - job is not propagated

When installing arc as root, and running arex as root, the internal submission job is not picked up by arex, and thus not propagated through its states. It stays in status ACCEPTED. The job.jobid.status file is present in controldir/accepted folder.

arcstat shows correctly that job is in ACCEPTED state.

What could be the reason for arex not picking up the job when arex is run as root? Job is picked up and propagated through its states if arc is installed as ordinary user, and run by ordinary user.

Example of arc.conf used:

[authgroup:staticdn]
subject=/DC=org/DC=nordugrid/DC=ARC/O=TestCA/CN=testuser

[common]
loglevel=5
x509_host_cert=/etc/grid-security/host-158.37.63.6-cert.pem
x509_host_key=/etc/grid-security/host-158.37.63.6-key.pem

[mapping]
unixmap=grid:grid all

[lrms]
lrms=fork

[arex]
controldir=/arc/control
sessiondir=/arc/session
runtimedir=/arc/runtime
shared_scratch=/arc
logfile=/arc/arc-logs/arex.log
maxjobs=100 10 10 -1 -1

[arex/cache]
cachedir=/arc/cache

[arex/data-staging]
maxtransfertries=10

[arex/ws]
loglevel=5
logfile=/arc/arc-logs/ws-interface.log

[arex/ws/emies]
allowaccess=staticdn

[gridftpd]
loglevel=5
logfile=/arc/arc-logs/gridftpd.log
globus_tcp_port_range=9000,9100
globus_udp_port_range=9000,9100

[gridftpd/jobs]
allowaccess=staticdn

[infosys]
loglevel=2
logfile=/arc/arc-logs/infoprovider.log


[queue:main]

[cluster]