Unable to get computed value with After Insert trigger - sql

Question

I'm using the FileTables feature and have setup a trigger to populate a FileProperties table whenever a file is copied to the SQL Server file share.
I'm trying to grab the file size (cached_file_size), and I get a value of zero. I set up the trigger the same way a standard FileTable does using DATALENTGH(file_stream). The code below is using the inserted tables' file_stream:
ALTER TRIGGER [dbo].[FileTable_Insert_Trigger]
ON [dbo].[Files]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
DECLARE #s_id UNIQUEIDENTIFIER,
#fs VARBINARY(MAX),
#nm NVARCHAR(255),
#fp NVARCHAR(MAX),
#cfs BIGINT,
#ft NVARCHAR(255);
SELECT #s_id = ins.stream_id FROM inserted ins;
SELECT #fs = ins.file_stream FROM inserted ins;
SELECT #nm = ins.name FROM inserted ins;
SELECT #fp = ins.file_stream.GetFileNamespacePath() FROM inserted ins;
SELECT #ft = ins.file_type FROM inserted ins;
SELECT #cfs = DATALENGTH(#fs);
INSERT INTO [FileProperties] (stream_id, [name], filepath, file_type,
cached_file_size, DateAdded, UserID)
VALUES (#s_id, #nm, #fp, #ft,
#cfs, CURRENT_TIMESTAMP, 1);
END
I've also tried grabbing the computed value directly from the FileTable:
SELECT #cfs = Files_1.cached_file_size
FROM [dbo].Files AS Files_1
WHERE Files_1.stream_id = #s_id;
Still getting zero. What am I missing here? Thank you.
[EDIT] I tried playing around with getting the DATALENGTH of other values such as the name (#nm) and stream_id (#s_id) and I do get the values correctly.