Not possible to update value of encrypted column - sql-server

Question

I have used Always Encrypted to encrypt values in a column. My connection string looks like this (everything is working fine and the client is able to decrypt the values):
Driver={ODBC Driver 13 for SQL Server};Server=10.10.10.1\INST2;Database=test;Trusted_Connection=yes;ColumnEncryption=Enabled;
Then I try to update one of the encrypted values using the following code:
ALTER PROCEDURE dbo.usp_SecurityUsers_GetDetails
(
#Firstname NVARCHAR(128)
)
AS
BEGIN;
UPDATE SecurityUsers
SET FirstName = #Firstname
WHERE login = 'system.export.service'
SELECT Login, FirstName, LastName
FROM SecurityUsers
END;
the SP is called like this:
Set cmd = Server.CreateObject("ADODB.Command")
Set cmd.ActiveConnection = conn
cmd.NamedParameters = True
cmd.CommandText = "[dbo].[usp_SecurityUsers_GetDetails]"
cmd.Parameters.Append cmd.CreateParameter("#Firstname", adLongVarWChar, adParamInput, 128, "system_text")
cmd.CommandType = adCmdStoredProc
Set recordSet = cmd.Execute
But I get the following error:
[Microsoft][ODBC Driver 13 for SQL Server][SQL Server]Encryption
scheme mismatch for columns/variables '#P1'. The encryption scheme for
the columns/variables is (encryption_type = 'PLAINTEXT') and the
expression near line '1' expects it to be (encryption_type =
'RANDOMIZED', encryption_algorithm_name =
'AEAD_AES_256_CBC_HMAC_SHA_256', column_encryption_key_name =
'CEK_SecurityLevelNormal', column_encryption_key_database_name =
'test') (or weaker).
It's very strange, because I am able to update the field if the code is not encapsulated in stored procedure and directly executed in the SQL Server Management Studio.
Also, calling the SP directly in the SSMS works.
EDIT:
Updating to .net 4.6.3 does not change anything. What I am seeing is, if I change the connection string ColumnEncryption=Enabled; to Column Encryption Setting=Enabled;, I am getting different error:
[Microsoft][ODBC Driver 13 for SQL Server][SQL Server]Operand type
clash: ntext is incompatible with nvarchar(128) encrypted with
(encryption_type = 'RANDOMIZED', encryption_algorithm_name =
'AEAD_AES_256_CBC_HMAC_SHA_256', column_encryption_key_name =
'CEK_SecurityLevelNormal', column_encryption_key_database_name =
'test')

Answer 1

I was feeling that the issue must be in the way I am trying to modify the data as I am able to read it. And it was so lame.
In my stored procedure I have nvarchar(256). In the ASP I am using adLongVarChar instead adVarWChar. The error seems more reasonable now:
Encryption scheme mismatch for columns/variables '#P1'.
The conclusion is one is able to read encrypted data and modify it using ADO and ODBC driver.