Guided rule expression editor text box splitting the expression in multiple text boxes separated by dot(.)

When creating a Guided Rule and using an expression editor as text and adding the expression in the text box but when we save it and close the editor and again open the same guided rule then the expression is getting split into multiple text boxes and those text boxes separated by a dot(.).
 
Like TextBox1[getNumber("$inputdata].TextBox2[ClassName].TextBox3[AGE","0"]
 
e.g: getNumber("$inputdata.ClassName.AGE","0")