Media Store record Not creating while saving image to Picture Folder in Android 10

So, I need to save image to the Picture folder. There will be some subfolders too. But every time I want to save an image it is giving this error:

Failed to create new mediaStore record

This is what I tried:

    @RequiresApi(Build.VERSION_CODES.Q)
    @Throws(IOException::class)
    fun saveMediaToStorage(context: Context, bitmap: Bitmap, format: CompressFormat, fName: String, folderName: String, extension: String) {
        //Generating a file name
        val filename = if (fName.contains("png")) fName.replace(".png", "") else fName.replace(".jpg", "")

        //Output stream
        var fos: OutputStream? = null
        val relativePath = Environment.DIRECTORY_PICTURES + File.separator + folderName

        Log.d(TAG, "saveMediaToStorage: Relative Path: $relativePath")

        //getting the contentResolver
        context.contentResolver?.also { resolver ->

            //Content resolver will process the contentvalues
            val contentValues = ContentValues().apply {

                //putting file information in content values
                put(MediaStore.MediaColumns.DISPLAY_NAME, filename)
                put(MediaStore.MediaColumns.MIME_TYPE, "image/$extension")
                put(MediaStore.MediaColumns.RELATIVE_PATH, relativePath)
            }

            //Inserting the contentValues to contentResolver and getting the Uri
            val imageUri= resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues) ?: 
            throw IOException("Failed to create new mediaStore record") // This line is triggering every time

            //Opening an outputstream with the Uri that we got
            fos = imageUri.let { resolver.openOutputStream(it) }
        }

        fos?.use {
            //Finally writing the bitmap to the output stream that we opened
            bitmap.compress(format, 100, it)
        }
    }

What I can understand is, the imageUri is coming null. But why so, afaik I am doing ok..

What can be the reason, where I am doing wrong.. Any help would be highly appreciated.