diff --git a/src/backend/app/central/central_crud.py b/src/backend/app/central/central_crud.py
index 22945aa9ed..6f2447c367 100644
--- a/src/backend/app/central/central_crud.py
+++ b/src/backend/app/central/central_crud.py
@@ -703,11 +703,6 @@ async def get_entities_data(
         # Rename '__id' to 'id'
         flattened_dict["id"] = flattened_dict.pop("__id")
 
-        # convert empty str osm_id to None
-        # when new entities are created osm_id will be empty
-        if flattened_dict.get("osm_id", "") == "":
-            flattened_dict["osm_id"] = None
-
         all_entities.append(flattened_dict)
 
     return all_entities
diff --git a/src/backend/app/central/central_schemas.py b/src/backend/app/central/central_schemas.py
index c67e526cf4..edb7fc819d 100644
--- a/src/backend/app/central/central_schemas.py
+++ b/src/backend/app/central/central_schemas.py
@@ -140,12 +140,34 @@ class EntityOsmID(BaseModel):
     id: str
     osm_id: Optional[int] = None
 
+    @field_validator("osm_id", mode="before")
+    @classmethod
+    def convert_osm_id(cls, value):
+        """Set osm_id to None if empty or invalid."""
+        if value in ("", " "):  # Treat empty strings as None
+            return None
+        try:
+            return int(value)  # Convert to integer if possible
+        except ValueError:
+            return value
+
 
 class EntityTaskID(BaseModel):
     """Map of Entity UUID to FMTM Task ID."""
 
     id: str
-    task_id: int
+    task_id: Optional[int] = None
+
+    @field_validator("task_id", mode="before")
+    @classmethod
+    def convert_task_id(cls, value):
+        """Set task_id to None if empty or invalid."""
+        if value in ("", " "):  # Treat empty strings as None
+            return None
+        try:
+            return int(value)  # Convert to integer if possible
+        except ValueError:
+            return value
 
 
 class EntityMappingStatus(EntityOsmID, EntityTaskID):
diff --git a/src/backend/app/projects/project_crud.py b/src/backend/app/projects/project_crud.py
index 1759cff1b3..f8b715f087 100644
--- a/src/backend/app/projects/project_crud.py
+++ b/src/backend/app/projects/project_crud.py
@@ -444,7 +444,8 @@ async def preview_split_by_square(
     Use a lambda function to remove the "z" dimension from each
     coordinate in the feature's geometry.
     """
-    boundary = merge_polygons(boundary)
+    if len(boundary["features"]) == 0:
+        boundary = merge_polygons(boundary)
 
     return await run_in_threadpool(
         lambda: split_by_square(