Could you please share the output of below command:
source /etc/pbs.conf;cat $PBS_HOME/sched_priv/sched_config | grep -v “#” | grep ^[a-zA-Z]
Also, if you could try to update the provision_policy in your sched_config and do a kill -HUP , see whether it helps the situation
provision_policy: “avoid_provision”
Reference: New node placement algorithm