diff --git a/pygeoapi_plugins/provider/sparql.py b/pygeoapi_plugins/provider/sparql.py
index ed12db6..3c823f1 100644
--- a/pygeoapi_plugins/provider/sparql.py
+++ b/pygeoapi_plugins/provider/sparql.py
@@ -292,11 +292,11 @@ def _clean_result(self, result):
                 if not v_:
                     continue
 
-                if not isinstance(v_, list):
+                if not isinstance(v_, list) and v_:
                     ret[_id][k] = [v_]
 
                 # If the current value is not already in the list, append it
-                if v_ not in [item['value'] for item in ret[_id][k]]:
+                if v_ not in [item['value'] for item in ret[_id][k]] and v_:
                     ret[_id][k].append(v_)
 
         return ret
@@ -411,8 +411,10 @@ def parse(value: str) -> list:
                   otherwise the original string.
         """
         if '|' in value:
+            LOGGER.debug('Splitting value by "|"')
             return value.split('|')
         elif ', ' in value:
+            LOGGER.debug('Splitting value by ", "')
             return value.split(', ')
         else:
             return value
@@ -432,6 +434,7 @@ def combine_lists(dict_data: dict):
         # Ensure all lists have the same length
         length = len(dict_data[keys[0]])
         if not all(len(dict_data[key]) == length for key in keys) and len(keys > 1):
+            LOGGER.debug('Returning un-mondified data')
             return dict_data
 
         # Combine the items into a list of dictionaries