Backout workforce compensation data transfer to core hr not working

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Hello experts,

I launched the Backout workforce compensation data transfer to core hr batch process to unlock compensation plan.

When I launched the Transfer workforce compensation data transfer to core hr for the first time, after the process finished the plan became read-only as expected.

However, I tried to purge the last transaction, but even if the plan status is under Updates Allowed Status, when entering in it I cannot modify any columns; they are still read-only.

What could it depend on? How can I edit those columns?

Thanks in advance for your time!