diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0c3aaeda1..dfa73fea5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -69,21 +69,30 @@ jobs:
       env:
         CC: gcc-13
         CXX: g++-13
+    - name: Run func tests (MPI, num_proc=1)
+      run: |
+        source scripts/run_mpi.sh
+      env:
+        PROC_COUNT: 1
+        OMP_NUM_THREADS: 3
     - name: Run func tests (MPI, num_proc=2)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 2
+        OMP_NUM_THREADS: 2
     - name: Run func tests (MPI, num_proc=3)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 3
+        OMP_NUM_THREADS: 1
     - name: Run func tests (MPI, num_proc=4)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 4
+        OMP_NUM_THREADS: 1
     - name: Run func tests (threads, num_threads=1)
       run: source scripts/run_threads.sh
       env:
@@ -211,21 +220,30 @@ jobs:
       env:
         CC: clang-19
         CXX: clang++-19
+    - name: Run func tests (MPI, num_proc=1)
+      run: |
+        source scripts/run_mpi.sh
+      env:
+        PROC_COUNT: 1
+        OMP_NUM_THREADS: 3
     - name: Run func tests (MPI, num_proc=2)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 2
+        OMP_NUM_THREADS: 2
     - name: Run func tests (MPI, num_proc=3)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 3
+        OMP_NUM_THREADS: 1
     - name: Run func tests (MPI, num_proc=4)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 4
+        OMP_NUM_THREADS: 1
     - name: Run tests (threads, num_threads=1)
       run: source scripts/run_threads.sh
       env:
@@ -358,6 +376,7 @@ jobs:
         source scripts/run_mpi.sh "--oversubscribe"
       env:
         PROC_COUNT: 2
+        OMP_NUM_THREADS: 2
     - name: Run tests (threads, num_threads=1)
       run: source scripts/run_threads.sh
       env:
@@ -489,21 +508,30 @@ jobs:
     - name: Ninja build
       run: |
         cmake --build build
+    - name: Run func tests (MPI, num_proc=1)
+      run: |
+        source scripts/run_mpi.sh
+      env:
+        PROC_COUNT: 1
+        OMP_NUM_THREADS: 3
     - name: Run func tests (MPI, num_proc=2)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 2
+        OMP_NUM_THREADS: 2
     - name: Run func tests (MPI, num_proc=3)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 3
+        OMP_NUM_THREADS: 1
     - name: Run func tests (MPI, num_proc=4)
       run: |
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 4
+        OMP_NUM_THREADS: 1
     - name: Run tests (threads, num_threads=1)
       run: source scripts/run_threads.sh
       env:
@@ -880,6 +908,7 @@ jobs:
         source scripts/run_mpi.sh
       env:
         PROC_COUNT: 2
+        OMP_NUM_THREADS: 2
     - name: Run tests (threads, num_threads=1)
       run: source scripts/run_threads.sh
       env: