Set Control Value Question

Hi,

I have a field that has a behavior of initially enabled unticked. Which means it is not supposed to be modified. Additionally, I have a upload file that will set the data of the said field using an active form flow and Set Control Value step. However, upon uploading and the field has been populated by the uploaded file, the field changed to enabled. Is this a normal behavior when using Set Control Value? How can I retain the field to disabled? Please refer to screenshot below:
Before upload:

After upload:

Active Form flow:

Thanks and Regards.
Ezra