diff --git a/validphys2/src/validphys/config.py b/validphys2/src/validphys/config.py
index e24950f39d..6530471051 100644
--- a/validphys2/src/validphys/config.py
+++ b/validphys2/src/validphys/config.py
@@ -1583,7 +1583,7 @@ def produce_group_dataset_inputs_by_metadata(
             if processed_metadata_group == "custom_group":
                 group_name = str(dsinput.custom_group)
             # special case of ALL, grouping everything together
-            if processed_metadata_group == "ALL":
+            elif processed_metadata_group == "ALL":
                 group_name = processed_metadata_group
             # otherwise try and take the key from the metadata.
             else:
diff --git a/validphys2/src/validphys/tests/baseline/test_plot_xq2_custom.png b/validphys2/src/validphys/tests/baseline/test_plot_xq2_custom.png
new file mode 100644
index 0000000000..cdf94a76a4
Binary files /dev/null and b/validphys2/src/validphys/tests/baseline/test_plot_xq2_custom.png differ
diff --git a/validphys2/src/validphys/tests/test_plots.py b/validphys2/src/validphys/tests/test_plots.py
index 72f78b0dfb..004514c71b 100644
--- a/validphys2/src/validphys/tests/test_plots.py
+++ b/validphys2/src/validphys/tests/test_plots.py
@@ -56,14 +56,40 @@ def test_plot_xq2():
     metadata_group = "experiment"
     dataset_inputs = [
         {'dataset': 'NMC'},
-        {'dataset': 'ATLASTTBARTOT', 'cfac':['QCD']},
-        {'dataset': 'CMSZDIFF12', 'cfac':('QCD', 'NRM'), 'sys':10}    
-        ]    
-        
+        {'dataset': 'ATLASTTBARTOT', 'cfac': ['QCD']},
+        {'dataset': 'CMSZDIFF12', 'cfac': ('QCD', 'NRM'), 'sys': 10},
+    ]
+
     return API.plot_xq2(
-            theoryid=theoryid,
-            use_cuts=use_cuts,
-            dataset_inputs=dataset_inputs,
-            display_cuts=display_cuts,
-            marker_by=marker_by,
-            metadata_group=metadata_group)
+        theoryid=theoryid,
+        use_cuts=use_cuts,
+        dataset_inputs=dataset_inputs,
+        display_cuts=display_cuts,
+        marker_by=marker_by,
+        metadata_group=metadata_group,
+    )
+
+@pytest.mark.linux
+@pytest.mark.mpl_image_compare
+def test_plot_xq2_custom():
+    theoryid = THEORYID
+    use_cuts = "nocuts"
+    display_cuts = False
+
+    marker_by = "group"
+    metadata_group = "custom_group"
+
+    dataset_inputs = [
+        {'dataset': 'NMC', 'custom_group': 'one'},
+        {'dataset': 'ATLASTTBARTOT', 'cfac': ['QCD'], 'custom_group': 'one'},
+        {'dataset': 'CMSZDIFF12', 'cfac': ('QCD', 'NRM'), 'sys': 10, 'custom_group': 'two'},
+    ]
+
+    return API.plot_xq2(
+        theoryid=theoryid,
+        use_cuts=use_cuts,
+        dataset_inputs=dataset_inputs,
+        display_cuts=display_cuts,
+        marker_by=marker_by,
+        metadata_group=metadata_group,
+    )