Hi @FrankWoody ,
Please use DAX to create a new table.
UNION ( Table2, FILTER ( Table1, NOT Table1[task] IN VALUES ( Table2[task] ) ) )
After updating the data source, Table 1:
If the problem is still not resolved, please provide detailed error information or the expected result you expect. Let me know immediately, looking forward to your reply.
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.