Access Update query with left join and group by - ms-access

Question

The query that selects the 42 unique task codes from [Task_History_Report_063018] that DO NOT currently exist in the [Task Code Dict] is
SELECT Task_History_Report_063018.[Task code]
FROM Task_History_Report_063018 LEFT JOIN [Task Code Dict]
ON Task_History_Report_063018.[Task code] = [Task Code Dict].[Task Code]
WHERE ((([Task Code Dict].[Task Code]) Is Null))
GROUP BY Task_History_Report_063018.[Task code];
When I convert this to the following update query:
UPDATE Task_History_Report_063018 LEFT JOIN [Task Code Dict]
ON Task_History_Report_063018.[Task code] = [Task Code Dict].[Task Code]
SET [Task Code Dict].[Task Code] = [Task_History_Report_063018].[Task code]
WHERE ((([Task Code Dict].[Task Code]) Is Null));
It attempts to update the dictionary with 201 NON-UNIQUE task codes. These are the 42 unique codes, expanded by their duplicates.
I tried:
UPDATE (SELECT Task_History_Report_063018.[Task code]
FROM Task_History_Report_063018
GROUP BY Task_History_Report_063018.[Task code]) as GroupedTasks
LEFT JOIN [Task Code Dict]
ON GroupedTasks.[Task code] = [Task Code Dict].[Task Code] SET [Task Code Dict].[Task Code] = GroupedTasks.[Task code]
WHERE ((([Task Code Dict].[Task Code]) Is Null));
When I select the Datasheet View I see the 42 null records for the corresponding unique task codes that are new, but when I attempt to execute I get an error that says:
Operation must use an updateable query.
I think this question was addressed here for MySQL, but the syntax didn't totally translate... MySQL Update query with left join and group by

Answer 1

Okay, fixed this. For some reason I was trying to do an update query when I was supposed to be doing and append. This got the job done:
INSERT INTO [Task Code Dict] ( [Task Code] )
SELECT DISTINCT Task_History_Report_063018.[Task code]
FROM Task_History_Report_063018 LEFT JOIN [Task Code Dict]
ON Task_History_Report_063018.[Task code] = [Task Code Dict].[Task Code]
WHERE ((([Task Code Dict].[Task Code]) Is Null));