I am fetching data using Python Tool and writing it to the dataframe. Some of the fields are in JSON format

which I need to normalize. For this, I am using Formula Tool to remove first and last square brackets ([]). However, when I am using Parse Tool, I am not getting anything as in the screenshot.

My workflow is as following:

I have uploaded the results before formula tool as well.
Any helps would be really appreciated!
Thanks in advance