Slurm only running 6 out of 12 array jobs concurrently on my 12-core PC system

I have a 12-core laptop (6 physical cores with hyperthreading) running Slurm for local job scheduling. When I submit job arrays requesting all 12 cores to be used simultaneously, Slurm consistently only runs 6 jobs concurrently, despite the system having 12 logical cores and sufficient memory.

I've tried multiple approaches:

Explicitly setting lower memory requirements:

#SBATCH --mem-per-cpu=100M

Using the --oversubscribe flag:

#SBATCH --oversubscribe

Explicitly setting CPU parameters:

#SBATCH --cpus-per-task=1
#SBATCH --threads-per-core=2

Checked that my partition allows oversubscription:

PartitionName=debug Nodes=thoma-Lenovo-Legion-5-15IMH05H Default=YES MaxTime=INFINITE State=UP OverSubscribe=YES

None of these approaches allowed more than 6 jobs to run concurrently.

My system is a Lenovo Legion 5 laptop running Ubuntu, with the following Slurm configuration:

SelectType              = select/cons_tres
SelectTypeParameters    = CR_CORE_MEMORY
MaxTasksPerNode         = 512
DefMemPerNode           = UNLIMITED
CPUAlloc=0 CPUEfctv=12 CPUTot=12
RealMemory=7846 AllocMem=0 FreeMem=123 Sockets=1 Boards=1

Here's my slurm program -

#!/bin/bash
#SBATCH --job-name=core_test
#SBATCH --array=1-12%12
#SBATCH --output=core_test_%A_%a.log
#SBATCH --cpus-per-task=1
#SBATCH --mem-per-cpu=500M #I don't like this constraint
#SBATCH --time=00:05:00
#SBATCH --hint=nomultithread  # This tells Slurm to avoid using hyperthreading

echo "Starting task $SLURM_ARRAY_TASK_ID at $(date)"
python test_parallel.py
echo "Task $SLURM_ARRAY_TASK_ID completed at $(date)"