Updating position codes on assignments via HDL

Summary:

Updating position codes on assignments via HDL

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We need to move 600 employees to a different position. I'm trying to do this via HDL, and I'm getting You must enter a valid value for the Action Code field. I know the value (ASG_CHANGE) is valid and active. I have tried various versions, using IDs vs user keys and I can't get passed this error

I have an SR logged as well, but thought I would try here as well.

Here's the HDL I tried and that was provided from the SR and I still get the same error: You must enter a valid value for the Action Code field.