I have tried this but after the formula saves and validate, the new column appears blank. I am not sure the linked approach is not working
Possible to share screenshots of the formula you are using?
We just checked and it working fine for our with JSON column in sheets and using a Formula column to extract keywords from JSON column in Formula column.
Also, if your JSON column doesn’t have any value than Formula column referencing that column will also not have any value.
Refer below screenshots for reference -
Sheet Screenshot have 2 columns - json2 is JSON column and jsonformula2 is Formula column
Formula used in formula column is as below
And, value of 1st row of JSON column is as below
second row doesn’t have any json value hence 2nd row is empty
Hope this helps!