diff --git a/ISOv4Plugin/ExtensionMethods/ExtensionMethods.cs b/ISOv4Plugin/ExtensionMethods/ExtensionMethods.cs
index 66a5615..0949024 100644
--- a/ISOv4Plugin/ExtensionMethods/ExtensionMethods.cs
+++ b/ISOv4Plugin/ExtensionMethods/ExtensionMethods.cs
@@ -95,6 +95,13 @@ public static bool ReverseEquals(this string s1, string s2)
             return true;
         }
 
+        /// <summary>
+        /// Matches NumericRepresentation by code, accounting for null representation code
+        /// </summary>
+        public static bool ContainsCode(this ApplicationDataModel.Representations.Representation representation, string code)
+        {
+            return representation?.Code != null && representation.Code.Contains(code);
+        }
 
         /// <summary>
         /// Looks up unit, converts and loads representation
diff --git a/ISOv4Plugin/Mappers/TimeLogMapper.cs b/ISOv4Plugin/Mappers/TimeLogMapper.cs
index f0eccf2..4922ace 100644
--- a/ISOv4Plugin/Mappers/TimeLogMapper.cs
+++ b/ISOv4Plugin/Mappers/TimeLogMapper.cs
@@ -409,8 +409,7 @@ protected IEnumerable<OperationData> ImportTimeLog(ISOTask loggedTask, ISOTimeLo
                         operationData.GetDeviceElementUses = x => operationData.DeviceElementUses.Where(s => s.Depth == x).ToList();
                         operationData.PrescriptionId = prescriptionID;
                         operationData.OperationType = GetOperationTypeFromProductCategory(productIDs) ??
-                                                      GetOperationTypeFromWorkingDatas(workingDatas) ??
-                                                      GetOperationTypeFromLoggingDevices(time);
+                                                      OverrideOperationTypeFromWorkingDatas(GetOperationTypeFromLoggingDevices(time), workingDatas);
                         operationData.ProductIds = productIDs;
                         if (!useDeferredExecution)
                         {
@@ -428,22 +427,25 @@ protected IEnumerable<OperationData> ImportTimeLog(ISOTask loggedTask, ISOTimeLo
             return null;
         }
 
-        private OperationTypeEnum? GetOperationTypeFromWorkingDatas(List<WorkingData> workingDatas)
+        private OperationTypeEnum OverrideOperationTypeFromWorkingDatas(OperationTypeEnum deviceOperationType, List<WorkingData> workingDatas)
         {
             //Harvest/ForageHarvest omitted intentionally to be determined from machine type vs. working data
-            if (workingDatas.Any(w => w.Representation.Code.Contains("Seed")))
+            if (workingDatas.Any(w => w.Representation.ContainsCode("Seed")))
             {
                 return OperationTypeEnum.SowingAndPlanting;
             }
-            else if (workingDatas.Any(w => w.Representation.Code.Contains("Tillage")))
+            else if (workingDatas.Any(w => w.Representation.ContainsCode("Tillage")))
             {
                 return OperationTypeEnum.Tillage;
             }
-            if (workingDatas.Any(w => w.Representation.Code.Contains("AppRate")))
+            if (workingDatas.Any(w => w.Representation.ContainsCode("AppRate")))
             {
-                return OperationTypeEnum.Unknown; //We can't differentiate CropProtection from Fertilizing, but prefer unkonwn to letting implement type set to SowingAndPlanting
+                if (deviceOperationType != OperationTypeEnum.Fertilizing && deviceOperationType != OperationTypeEnum.CropProtection)
+                {
+                    return OperationTypeEnum.Unknown; //We can't differentiate CropProtection from Fertilizing, but prefer unknown to letting implement type set to SowingAndPlanting
+                }
             }
-            return null;
+            return deviceOperationType;
         }
 
         private List<List<string>> SplitElementsByProductProperties(Dictionary<string, List<ISOProductAllocation>> productAllocations, HashSet<string> loggedDeviceElementIds, ISODevice dvc)
@@ -682,9 +684,6 @@ private void AddProductAllocationsForDeviceElement(Dictionary<string, Dictionary
 
             switch (productCategories.FirstOrDefault())
             {
-                case CategoryEnum.Variety:
-                    return OperationTypeEnum.SowingAndPlanting;
-
                 case CategoryEnum.Fertilizer:
                 case CategoryEnum.NitrogenStabilizer:
                 case CategoryEnum.Manure:
@@ -722,7 +721,9 @@ private OperationTypeEnum GetOperationTypeFromLoggingDevices(ISOTime time)
                 }
             }
 
-            DeviceOperationType deviceType = representedTypes.FirstOrDefault(t => t.ClientNAMEMachineType >= 2 && t.ClientNAMEMachineType <= 11);
+            DeviceOperationType deviceType = representedTypes.FirstOrDefault(t => t.ClientNAMEMachineType >= 2 && t.ClientNAMEMachineType <= 11 &&
+                t.OperationType != OperationTypeEnum.Unknown);
+
             if (deviceType != null)
             {
                 //2-11 represent known types of operations