Plot rendering error: 'NoneType' object has no attribute 'bbox'; metadata = {'Entries': 4493943, 'Name': 'InjVcalDiff', 'Overflow': 4203731.0, 'Type': 'Histo2d', 'Underflow': 0.0, 'x': {'AxisTitle': 'InjVcalDiff', 'Bins': 51, 'High': 505.0, 'Low': -5.0}, 'y': {'AxisTitle': 'Occupancy', 'Bins': 49, 'High': 49.5, 'Low': 0.5}, 'z': {'AxisTitle': 'Number of pixels'}}