diff --git a/.gitignore b/.gitignore
index 67ce5235a..55283e5d8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -129,6 +129,7 @@ dmypy.json
 # CORE reports
 CORE-Report*.xlsx
 CORE-Report*.json
+CORE-Report*.csv
 # Pyre type checker
 .pyre/
 
diff --git a/cdisc_rules_engine/utilities/data_processor.py b/cdisc_rules_engine/utilities/data_processor.py
index c7c846bd0..d85c00533 100644
--- a/cdisc_rules_engine/utilities/data_processor.py
+++ b/cdisc_rules_engine/utilities/data_processor.py
@@ -59,13 +59,16 @@ def filter_if_present(df: DatasetInterface, col: str, filter_value):
             pass
         except ValueError:
             pass
+        has_filter = bool(filter_value) and not (
+            isinstance(filter_value, float) and pd.isna(filter_value)
+        )
         return (
             df.from_dict(
                 df[
                     DataProcessor.convert_float_merge_keys(df[col]) == str(filter_value)
                 ].to_dict()
             )
-            if filter_value
+            if has_filter
             else df
         )
 
@@ -94,7 +97,7 @@ def filter_relrec_for_domain(
 
     @staticmethod
     def merge_on_relrec_record(
-        relrec_row: pd.Series,
+        relrec_row: dict,
         left_dataset: DatasetInterface,
         datasets: List[dict],
         dataset_preprocessor: DatasetPreprocessor,
@@ -178,15 +181,15 @@ def merge_relrec_datasets(
     ) -> DatasetInterface:
         """
         1. Find each record within relrec_dataset where RDOMAIN matches the
-          left_dataset_domain_name
+        left_dataset_domain_name
         2. Join each of these (left) records with all other (right) records in
-          relrec_dataset sharing the same STUDYID, USUBJID, RELID
+        relrec_dataset sharing the same STUDYID, USUBJID, RELID
         3. For each record in this new dataset:
             1. Filter the left and right datasets by the criteria
             2. Rename the right dataset columns with wildcards and a "RELREC." dataset
-              specifier
+            specifier
             3. Join the records referenced by the left side with the records referenced
-              by the right side
+            by the right side
             4. Union the results
         """
         relrec_for_domain = DataProcessor.filter_relrec_for_domain(
@@ -196,7 +199,7 @@ def merge_relrec_datasets(
             DataProcessor.merge_on_relrec_record(
                 relrec_row, left_dataset, datasets, dataset_preprocessor, wildcard
             )
-            for _, relrec_row in relrec_for_domain.iterrows()
+            for relrec_row in relrec_for_domain.to_dict("records")
         ]
         result = (
             objs[0].concat(objs[1:], ignore_index=True)