jsonvalidator_isvalid and a!fromjson validations do not match

Hi Team

We use the jsonvalidator_isvalid() function to validate if the given text is in JSON format or not and then we use a!fromjson() function to format it.

We get "true" boolean value in output for jsonvalidator_isvalid() function but a!fromjson() gives us error : "The jsonText parameter was not valid JSON."

We also get  "true" boolean value in output for isjsonvalid() function.

How can we resolve this? Appian version 21.1

Text used for validation is in format similar to the one mentioned below : 

"You have issue:test to fix." "Test Description:" "test issue..." "For more details login to site"

NOTE : We also have valid json texts, null texts and string values to validate.