diff --git a/.github/workflows/nestbuildmatrix.yml b/.github/workflows/nestbuildmatrix.yml
index 0d98db8f1b..3990524259 100644
--- a/.github/workflows/nestbuildmatrix.yml
+++ b/.github/workflows/nestbuildmatrix.yml
@@ -49,6 +49,7 @@ jobs:
              cpp_compiler: "clang"
 
      steps:
+       - uses: actions/checkout@v2
 
        # Steps represent a sequence of tasks that will be executed as part of the job
        - name: Checkout repo content
@@ -137,3 +138,8 @@ jobs:
            python extras/parse_build_log.py gha_build.sh.log ${{ github.workspace }}
          env:
            xNEST_BUILD_TYPE: FULL
+
+       - name: tmate
+         if: ${{ failure() }}
+         uses: mxschmitt/action-tmate@v3
+
diff --git a/pynest/nest/tests/test_visualization.py b/pynest/nest/tests/test_visualization.py
index b49538b245..e39ee1cdc2 100644
--- a/pynest/nest/tests/test_visualization.py
+++ b/pynest/nest/tests/test_visualization.py
@@ -49,6 +49,8 @@
 except ImportError:
     HAVE_PANDAS = False
 
+import nest.voltage_trace as nvtrace
+import nest.raster_plot as nraster
 
 class VisualizationTestCase(unittest.TestCase):
     def nest_tmpdir(self):
@@ -88,27 +90,36 @@ def voltage_trace_verify(self, device):
             x_data, y_data = line.get_data()
             # Check that times are correct
             self.assertEqual(list(x_data), list(np.unique(device.get('events', 'times'))))
+            print("times:")
+            print(x_data)
+            print(list(np.unique(device.get('events', 'times'))))
             # Check that voltmeter data corresponds to the lines in the plot
             self.assertTrue(all(np.isclose(ref_vm, y_data)))
+            print("v_m:")
+            print(ref_vm)
+            print(y_data)
         plt.close(ax.get_figure())
 
     @unittest.skipIf(not PLOTTING_POSSIBLE, 'Plotting impossible because matplotlib or display missing')
     def test_voltage_trace_from_device(self):
         """Test voltage_trace from device"""
-        import nest.voltage_trace as nvtrace
         nest.ResetKernel()
         nodes = nest.Create('iaf_psc_alpha', 2)
         pg = nest.Create('poisson_generator', 1, {'rate': 1000.})
         device = nest.Create('voltmeter')
         nest.Connect(pg, nodes)
         nest.Connect(device, nodes)
+        wfwf = nest.Create('spike_recorder')
+        nest.Connect(pg, wfwf)
         nest.Simulate(100)
 
         # Test with data from device
+        print("From device:--------------------------------------")
+        print("Recording times: " + str(device.get('events')['times']))
         nest.voltage_trace.from_device(device)
         self.voltage_trace_verify(device)
 
-        # Test with fata from file
+        # Test with data from file
         vm = device.get('events')
         data = np.zeros([len(vm['senders']), 3])
         data[:, 0] = vm['senders']
@@ -116,7 +127,10 @@ def test_voltage_trace_from_device(self):
         data[:, 2] = vm['V_m']
         filename = os.path.join(self.nest_tmpdir(), 'voltage_trace.txt')
         self.filenames.append(filename)
+        print("FILENAME::::::::::::::::: " + str(filename))
         np.savetxt(filename, data)
+
+        print("From file:--------------------------------------")
         nest.voltage_trace.from_file(filename)
         self.voltage_trace_verify(device)
 
@@ -150,7 +164,6 @@ def spike_recorder_raster_verify(self, sr_ref):
     @unittest.skipIf(not PLOTTING_POSSIBLE, 'Plotting impossible because matplotlib or display missing')
     def test_raster_plot(self):
         """Test raster_plot"""
-        import nest.raster_plot as nraster
 
         sr, sr_to_file = self.spike_recorder_data_setup(to_file=True)
         spikes = sr.get('events')
diff --git a/pynest/nest/voltage_trace.py b/pynest/nest/voltage_trace.py
index b466c6e219..ed067d787d 100644
--- a/pynest/nest/voltage_trace.py
+++ b/pynest/nest/voltage_trace.py
@@ -185,7 +185,10 @@ def from_device(detec, neurons=None, title=None, grayscale=False,
 
         plotids = []
         for neuron in neurons:
+            print("times[neuron] = " + str(times[neuron]))
+            print("timefactor = " + str(timefactor))
             time_values = numpy.array(times[neuron]) / timefactor
+            print("time_values = " + str(time_values))
 
             if grayscale:
                 line_style = "k"
@@ -197,6 +200,9 @@ def from_device(detec, neurons=None, title=None, grayscale=False,
                     plt.plot(time_values, voltages[neuron],
                              line_style, label="Neuron %i" % neuron)
                 )
+                ax = plt.gca()
+                for line_idx, line in enumerate(ax.lines):
+                    print("line " + str(line_idx) + " xdata = " + str(line.get_data()[0]))
             except KeyError:
                 print("INFO: Wrong ID: {0}".format(neuron))