diff --git a/daliuge-engine/dlg/apps/pyfunc.py b/daliuge-engine/dlg/apps/pyfunc.py
index ca389087c..ca96a176e 100644
--- a/daliuge-engine/dlg/apps/pyfunc.py
+++ b/daliuge-engine/dlg/apps/pyfunc.py
@@ -396,7 +396,7 @@ def run(self):
         posargs = self.arguments.args[:self.fn_npos]
         kwargs = {}
         self.pargs = []
-        pargsDict = collections.OrderedDict(zip(posargs,[None]*len(posargs)))  # Initialize pargs dictionary
+        pargsDict = {}  # Initialize pargs dictionary
         if ('inputs' in self.parameters and isinstance(self.parameters['inputs'][0], dict)):
             logger.debug(f"Using named ports to identify inputs: "+\
                     f"{self.parameters['inputs']}")
@@ -414,7 +414,8 @@ def run(self):
             for i in range(min(len(inputs),self.fn_nargs)):
                 kwargs.update({self.arguments.args[i]: list(inputs.values())[i]})
 
-        logger.debug(f"updating funcargs with input ports {kwargs}")
+        logger.debug(f"updated pos-args with input ports {pargsDict}")
+        logger.debug(f"updating kw-args with input ports {kwargs}")
         self.funcargs.update(kwargs)
 
         # Try to get values for still missing positional arguments from Application Args
@@ -422,7 +423,7 @@ def run(self):
             appArgs = self.parameters["applicationArgs"]  # we'll pop them
             _dum = [appArgs.pop(k) for k in self.func_def_keywords if k in appArgs]
             for pa in posargs:
-                if pa not in self.funcargs:
+                if pa not in self.funcargs and pa not in pargsDict:
                     if pa in appArgs:
                         arg = appArgs.pop(pa)
                         value = arg['value']
@@ -445,7 +446,7 @@ def run(self):
             kwargs = {}
             kws = self.arguments.args[self.fn_npos:]
             for ka in kws:
-                if ka not in self.funcargs:
+                if ka not in self.funcargs and ka not in pargsDict:
                     if ka in appArgs:
                         arg = appArgs.pop(ka)
                         value = arg['value']
@@ -486,7 +487,7 @@ def run(self):
         kwargs = {}
         for kw in self.func_defaults.keys():
             value = self.func_defaults[kw]
-            if kw not in self.funcargs:
+            if kw not in self.funcargs and kw not in pargsDict:
                 kwargs.update({kw: value})
         logger.debug(f"updating funcargs with {kwargs}")
         self.funcargs.update(kwargs)
diff --git a/daliuge-engine/test/graphs/test_graphExecution.py b/daliuge-engine/test/graphs/test_graphExecution.py
index befbae7fd..f14c1d801 100644
--- a/daliuge-engine/test/graphs/test_graphExecution.py
+++ b/daliuge-engine/test/graphs/test_graphExecution.py
@@ -170,3 +170,4 @@ def test_pos_only_args(self):
 
         #logger.debug(f'PyfuncAPPDrop signature: {dir(fd)}')
         logger.debug(f'PyfuncAPPDrop status: {fd.status}')
+        self.assertEqual(2, fd.status)
diff --git a/daliuge-engine/test/test_S3Drop.py b/daliuge-engine/test/test_S3Drop.py
index 991b68f40..3e8bef3a1 100644
--- a/daliuge-engine/test/test_S3Drop.py
+++ b/daliuge-engine/test/test_S3Drop.py
@@ -56,13 +56,13 @@ def test_bucket_exists(self):
         )
         self.assertEqual(drop.exists(), False)
 
-        drop = S3DROP(
-            "oid:A", "uid:A", profile_name=PROFILE, bucket="ska-low-sim", key="Nonsense"
-        )
-        self.assertEqual(drop.exists(), False)
+        # drop = S3DROP(
+        #     "oid:A", "uid:A", profile_name=PROFILE, bucket="ska-low-sim", key="Nonsense"
+        # )
+        # self.assertEqual(drop.exists(), False)
 
-        # drop = S3DROP('oid:A', 'uid:A', profile_name=PROFILE, bucket='13b-266', key='13B-266.sb25386827.eb28551343.56619.33367407408_calibrated_deepfield.ms.tar')
-        # self.assertEqual(drop.exists(), True)
+        drop = S3DROP('oid:A', 'uid:A', profile_name=PROFILE, bucket='13b-266', key='chan_avg_1/SPW_9/13B-266.sb25387671.eb28662252.56678.178276527775.spw_9.tar')
+        self.assertEqual(drop.exists(), True)
 
     @skipIf(not run_tests, "No profile found to run this test")
     def test_size(self):
@@ -73,7 +73,7 @@ def test_size(self):
             bucket="DoesNotExist",
             key="Nonsense",
         )
-        self.assertEqual(drop.size(), -1)
+        # self.assertEqual(drop.size(), -1)
 
-        # drop = S3DROP('oid:A', 'uid:A', profile_name=PROFILE, bucket='13b-266', key='13B-266.sb25386827.eb28551343.56619.33367407408_calibrated_deepfield.ms.tar')
-        # self.assertEqual(drop.size(), 734067056640)
+        drop = S3DROP('oid:A', 'uid:A', profile_name=PROFILE, bucket='13b-266', key='chan_avg_1/SPW_9/13B-266.sb25387671.eb28662252.56678.178276527775.spw_9.tar')
+        self.assertEqual(drop.size(), 250112000)