When using the Xpath option to reference a JSON object attribute to mask within the embedded JSON document, the masking process (doesn't matter what function you use) is applying the given mask rule to the text representation of the path (example: "$['contries'][*]['state_or_provences'][*]['name']"), instead of applying the masking rule to the JSON Attribute text content found at the end of of that path.

TDM 4.7

Downloaded the latest version   FastDataMasker-4.7.3226.0.zip .  This has the fix.