Hi Thilina,
when using grid-editing (which calls tbl_replace.php), normally I see the generated UPDATE statement after my edit.
However, if my table uses a transformation (for example, a VARCHAR with a MIME type = text/plain and a Browser transformation = text/plain: substr), I don't see the generated UPDATE statement.
As a hint to debug this, I saw that PMA_getTransformationFunctionAndTransformationOptions() does not (always?) return an array, or an array with is correct to feed to $response->addJSON().